fix(frontend/Snackbar): announce correctly, pause timer on interaction

[sidvishnoi]

Changes proposed in this pull request

Multiple a11y fixes to Snackbar:

• Add accessible role and make sure it's reliably announced
• Ensure hide timer could be paused if user hovers (or focuses) over notification (it should stay, not disappear immediately if user is interacting). Also, increase timeout from 2s to 5s.
• Move Snackbar to start in tab-order, so one doesn't have to tab till end to interact with it (by that time, notification goes away)

In future, we can get rid of SnackbarAnnouncer when ariaNotify is better supported.

Context

Follow up of #3961

Checklist

• Related issues linked using fixes #number
• Tests added/updated
• Make sure that all checks pass
• Bruno collection updated (if necessary)
• Documentation issue created with user-docs label (if necessary)
• OpenAPI specs updated (if necessary)

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[github-actions]

🚀 Performance Test Results

Test Configuration:

• VUs: 4
• Duration: 1m0s

Test Metrics:

• Requests/s: 42.58
• Iterations/s: 14.19
• Failed Requests: 0.00% (0 of 2563)

📜 Logs

> performance@1.0.0 run-tests:testenv /home/runner/work/rafiki/rafiki/test/performance
> ./scripts/run-tests.sh -e test -k -q --vus 4 --duration 1m

Cloud Nine GraphQL API is up: http://localhost:3101/graphql
Cloud Nine Wallet Address is up: http://localhost:3100/
Happy Life Bank Address is up: http://localhost:4100/
cloud-nine-wallet-test-backend already set
cloud-nine-wallet-test-auth already set
happy-life-bank-test-backend already set
happy-life-bank-test-auth already set
     data_received..................: 925 kB 15 kB/s
     data_sent......................: 2.0 MB 33 kB/s
     http_req_blocked...............: avg=6.71µs   min=2.04µs   med=5.29µs   max=745.48µs p(90)=6.81µs   p(95)=7.63µs  
     http_req_connecting............: avg=322ns    min=0s       med=0s       max=244.43µs p(90)=0s       p(95)=0s      
     http_req_duration..............: avg=93.24ms  min=7.34ms   med=76.1ms   max=483.51ms p(90)=165.82ms p(95)=189.82ms
       { expected_response:true }...: avg=93.24ms  min=7.34ms   med=76.1ms   max=483.51ms p(90)=165.82ms p(95)=189.82ms
     http_req_failed................: 0.00%  ✓ 0         ✗ 2563
     http_req_receiving.............: avg=96.62µs  min=25.55µs  med=84.88µs  max=1.96ms   p(90)=122.24µs p(95)=164.67µs
     http_req_sending...............: avg=34.13µs  min=7.91µs   med=25.78µs  max=2.58ms   p(90)=40.75µs  p(95)=54.6µs  
     http_req_tls_handshaking.......: avg=0s       min=0s       med=0s       max=0s       p(90)=0s       p(95)=0s      
     http_req_waiting...............: avg=93.11ms  min=7.16ms   med=75.96ms  max=483.38ms p(90)=165.71ms p(95)=189.75ms
     http_reqs......................: 2563   42.581421/s
     iteration_duration.............: avg=281.48ms min=174.39ms med=269.09ms max=881.51ms p(90)=348.24ms p(95)=382.78ms
     iterations.....................: 854    14.188269/s
     vus............................: 4      min=4       max=4 
     vus_max........................: 4      min=4       max=4 

[sidvishnoi]

This is technically redundant, but practically useful. With Firefox in particular.