chore: export SDKs to gemini-api-oad/dist/<lang> via Copybara additional_g3_exports

[copybara-service]

chore: export SDKs to gemini-api-oad/dist/ via Copybara additional_g3_exports

• Add additional_g3_exports in labs/language/genai/interactions/openapi/copy.bara.sky to export all 6 SDKs (typescript, python, java, dotnet, go, cli) to dist/<lang> in google-gemini/gemini-api-oad.
• Extract shared file inclusion/exclusion lists into per-SDK common.bara.sky files and load() them in openapi/copy.bara.sky and each SDK's copy.bara.sky.
• Extract shared Copybara presubmit rules into labs/language/genai/interactions/openapi/gemini-api-oad.METADATA (with feedback_github_to_critique and 3600s timeouts) and include via include_presubmit across openapi/METADATA and all 6 SDK METADATA files.
• Add missing gen.lock files for sp_csharp and sp_go.

[adri22235]

Hi team! Quick heads-up: the conventionalcommits.org lint check failed on this PR because the commit message is missing a Conventional Commit type prefix (it currently starts directly with *export sdks...).

Updating the PR / commit title to something like:
chore(copybara): export SDKs to gemini-api-oad/dist/<lang> via additional_g3_exports

will immediately resolve the type may not be empty and subject may not be empty errors and turn the check green. Thanks!