v0.23.0

fix: set IsSensitive on meshstack_building_block_v2 inputs

Sensitive user inputs (STRING and CODE) sent by the deprecated
meshstack_building_block_v2 resource omitted IsSensitive on the outbound
MeshBuildingBlockInput. Because MeshBuildingBlockInput.UnmarshalJSON demotes a
secret from SecretOrAny.X to a plain SecretOrAny.Y when IsSensitive is false,
the secret was stripped on the mock client's JSON round-trip and the plaintext
leaked into value_string as a raw map instead of surfacing the backend hash.

Set IsSensitive on sensitive inputs so the secret stays in the X variant,
matching what the v3 resource does symmetrically via buildingBlockConverterOptions.
The real backend re-derives sensitivity from the definition, so this is a
correctness/mock-fidelity fix with no user-facing behavior change (no CHANGELOG
entry). Re-enables the previously mock-skipped v2 sensitive-input tests to run
in both mock and acceptance modes, asserting the surfaced value is the hash and
not the plaintext.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>