add AZS009: computed-only fields must not set input-only schema attributes

[katbyte]

New rule. A computed-only field (Computed: true, no Optional/Required) is filled from the API, so ValidateFunc, MaxItems, Default, ConflictsWith and the rest of the SDK's input-only list do nothing on it. The plugin SDK's InternalValidate already rejects those on the field that says Computed, but not on fields nested inside a computed-only block, not on an element schema's ValidateFunc, and not Optional/Required on nested fields. Those are the cases this catches, plus everything in a typed resource's Attributes(), which azurerm forces Computed at start-up.

-fix deletes the attribute's line, or turns a nested Optional/Required into Computed. On azurerm: 35 reports, all nested or element cases, zero top-level; the fix touches 11 files and the provider builds.

Also moves AZR009's deleteLine into lib/astx as DeleteLine so both rules share it, and carries the same skipp regex fix as #43 so typos passes here.