Add macro to support introspection on semantic view

[sfc-gh-yutliu]

Root cause:
DBT adapter does not support semantic view, so snowflake__get_columns_in_relation will fail if taking a semantic view as argument.

Solution:
Add customization macro of snowflake__get_columns_in_relation in dbt_semantic_view package to return empty column list instead of go to default describe table <semantic_view> to avoid Invalid object type: 'TABLE' issue.

Caveat:
customers need to add search_order: [dbt_semantic_view, dbt] (see dbt_project.yml change in this pr) to make the package override take precedent of dbt's implementation.

Tests:

• Without customized macro and overriding the search_order: [dbt_semantic_view, dbt], running macro debug_call_get_columns will fail.

(custom_vemv) ➜  integration_tests git:(yutliu-fix-issue-5) ✗ dbt run-operation debug_call_get_columns --args '{"model_name": "semantic_view_basic"}'
23:38:27  Running with dbt=1.9.4
23:38:28  Registered adapter: snowflake=1.9.2
23:38:28  Unable to do partial parsing because saved manifest not found. Starting full parse.
23:38:29  Found 10 models, 10 data tests, 1 seed, 2 operations, 2 sources, 601 macros
23:38:30  Encountered an error while running operation: Database Error
  002030 (42601): SQL compilation error:
  Invalid object type: 'TABLE'
(custom_vemv) ➜  integration_tests git:(yutliu-fix-issue-5) ✗ 

Running model dbt run --models union_table_refer_to_semantic_views will fail.

(custom_vemv) ➜  integration_tests git:(yutliu-fix-issue-5) ✗ dbt run --models union_table_refer_to_semantic_views 
00:14:04  Running with dbt=1.9.4
00:14:05  Registered adapter: snowflake=1.9.2
00:14:05  Unable to do partial parsing because saved manifest not found. Starting full parse.
00:14:06  Found 11 models, 10 data tests, 1 seed, 2 operations, 2 sources, 601 macros
00:14:06  
00:14:06  Concurrency: 4 threads (target='snowflake')
00:14:06  
00:14:20  1 of 2 START hook: dbt_semantic_view_integration_tests.on-run-start.0 .......... [RUN]
00:14:20  1 of 2 OK hook: dbt_semantic_view_integration_tests.on-run-start.0 ............. [OK in 1.74s]
00:14:20  2 of 2 START hook: dbt_semantic_view_integration_tests.on-run-start.1 .......... [RUN]
00:14:20  2 of 2 OK hook: dbt_semantic_view_integration_tests.on-run-start.1 ............. [OK in 0.43s]
00:14:20  
00:14:20  1 of 1 START sql table model yutliu.union_table_refer_to_semantic_views ........ [RUN]
00:14:20  1 of 1 ERROR creating sql table model yutliu.union_table_refer_to_semantic_views  [ERROR in 0.16s]
00:14:21  
00:14:21  Finished running 2 project hooks, 1 table model in 0 hours 0 minutes and 14.97 seconds (14.97s).
00:14:21  
00:14:21  Completed with 1 error, 0 partial successes, and 0 warnings:
00:14:21  
00:14:21    Database Error in model union_table_refer_to_semantic_views (models/union_table_refer_to_semantic_views.sql)
  002030 (42601): SQL compilation error:
  Invalid object type: 'TABLE'
00:14:21  
00:14:21  Done. PASS=2 WARN=0 ERROR=1 SKIP=0 TOTAL=3
(custom_vemv) ➜  integration_tests git:(yutliu-fix-issue-5) ✗ 

• With customized macro and overriding the search_order: [dbt_semantic_view, dbt], running macro debug_call_get_columns will succeed.

(custom_vemv) ➜  integration_tests git:(yutliu-fix-issue-5) dbt run-operation debug_call_get_columns --args '{"model_name": "semantic_view_basic"}'
00:09:27  Running with dbt=1.9.4
00:09:27  Registered adapter: snowflake=1.9.2
00:09:28  Found 11 models, 10 data tests, 1 seed, 2 operations, 2 sources, 601 macros
00:09:29  override test -> temp.yutliu.semantic_view_basic columns=0
(custom_vemv) ➜  integration_tests git:(yutliu-fix-issue-5) 

Running model dbt run --models union_table_refer_to_semantic_views will fail, but not the error Invalid object type: 'TABLE'.

(custom_vemv) ➜  integration_tests git:(yutliu-fix-issue-5) dbt run --models union_table_refer_to_semantic_views                                   
00:11:45  Running with dbt=1.9.4
00:11:46  Registered adapter: snowflake=1.9.2
00:11:46  Found 11 models, 10 data tests, 1 seed, 2 operations, 2 sources, 601 macros
00:11:46  
00:11:46  Concurrency: 4 threads (target='snowflake')
00:11:46  
00:11:59  1 of 2 START hook: dbt_semantic_view_integration_tests.on-run-start.0 .......... [RUN]
00:11:59  1 of 2 OK hook: dbt_semantic_view_integration_tests.on-run-start.0 ............. [OK in 1.87s]
00:11:59  2 of 2 START hook: dbt_semantic_view_integration_tests.on-run-start.1 .......... [RUN]
00:11:59  2 of 2 OK hook: dbt_semantic_view_integration_tests.on-run-start.1 ............. [OK in 0.26s]
00:11:59  
00:11:59  1 of 1 START sql table model yutliu.union_table_refer_to_semantic_views ........ [RUN]
00:12:00  1 of 1 ERROR creating sql table model yutliu.union_table_refer_to_semantic_views  [ERROR in 1.06s]
00:12:01  
00:12:01  Finished running 2 project hooks, 1 table model in 0 hours 0 minutes and 15.11 seconds (15.11s).
00:12:01  
00:12:01  Completed with 1 error, 0 partial successes, and 0 warnings:
00:12:01  
00:12:01    Database Error in model union_table_refer_to_semantic_views (models/union_table_refer_to_semantic_views.sql)
  000002 (0A000): Unsupported feature 'SELECT FROM SEMANTIC VIEW'.
  compiled code at target/run/dbt_semantic_view_integration_tests/models/union_table_refer_to_semantic_views.sql
00:12:01  
00:12:01  Done. PASS=2 WARN=0 ERROR=1 SKIP=0 TOTAL=3