Improve Env abstraction

[mbg]

This PR cherry-picks some changes from #3994 and addresses review feedback there related to the new Env abstraction.

Main changes

• Functions in action-utils.ts can now be provided with an Env to use. For backwards-compatibility, they default to getEnv() if none is provided.
• Split the Env interface into an Env class and a ReadOnlyEnv class.
• Moved more code related to environment variables to environment.ts

Out of scope

• Using the new abstractions (e.g. ReadOnlyEnv or supplying functions in action-utils.ts with new arguments) everywhere that makes sense.

Risk assessment

For internal use only. Please select the risk level of this change:

• Low risk: Changes are fully under feature flags, or have been fully tested and validated in pre-production environments and are highly observable, or are documentation or test only.

Which use cases does this change impact?

Workflow types:

• Advanced setup - Impacts users who have custom CodeQL workflows.
• Managed - Impacts users with dynamic workflows (Default Setup, Code Quality, ...).

Products:

• Code Scanning - The changes impact analyses when analysis-kinds: code-scanning.
• Code Quality - The changes impact analyses when analysis-kinds: code-quality.
• Other first-party - The changes impact other first-party analyses.
• Third-party analyses - The changes affect the upload-sarif action.

Environments:

• Dotcom - Impacts CodeQL workflows on github.com and/or GitHub Enterprise Cloud with Data Residency.
• GHES - Impacts CodeQL workflows on GitHub Enterprise Server.

How did/will you validate this change?

• Unit tests - I am depending on unit test coverage (i.e. tests in .test.ts files).
• End-to-end tests - I am depending on PR checks (i.e. tests in pr-checks).

If something goes wrong after this change is released, what are the mitigation and rollback strategies?

• Rollback - Change can only be disabled by rolling back the release or releasing a new version with a fix.

How will you know if something goes wrong after this change is released?

• Telemetry - I rely on existing telemetry or have made changes to the telemetry.
  • Dashboards - I will watch relevant dashboards for issues after the release. Consider whether this requires this change to be released at a particular time rather than as part of a regular release.
  • Alerts - New or existing monitors will trip if something goes wrong with this change.

Are there any special considerations for merging or releasing this change?

• No special considerations - This change can be merged at any time.

Merge / deployment checklist

• Confirm this change is backwards compatible with existing workflows.
• Consider adding a changelog entry for this change.
• Confirm the readme and docs have been updated if necessary.

[Copilot]

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Pull request overview

This PR refactors and centralizes environment-variable handling by introducing ReadOnlyEnv alongside a writable Env, moving GitHub Actions env-var constants into environment.ts, and updating key helpers/tests to support environment injection (defaulting to getEnv() for compatibility).

Changes:

• Reworked the environment abstraction: added ReadOnlyEnv, turned Env into a class, and added ActionsEnvVars/new EnvVar entries in src/environment.ts.
• Updated actions-util.ts and api-client.ts to accept an injectable environment (defaulting to getEnv()), and adjusted tests accordingly.
• Kept backward compatibility by re-exporting env helpers from src/util.ts.

Show a summary per file

File	Description
src/environment.ts	Introduces ReadOnlyEnv/Env classes, adds ActionsEnvVars, and expands EnvVar constants.
src/util.ts	Removes local env helper implementations and re-exports env helpers for backwards compatibility.
src/actions-util.ts	Switches env access to the new Env abstraction and threads an injectable env through several helpers.
src/api-client.ts	Allows getApiDetails/getApiClient to read required env vars via an injected ReadOnlyEnv.
src/testing-utils.ts	Updates test helpers to support setting Actions env vars via Env.
src/api-client.test.ts	Updates tests to pass a test environment object rather than stubbing required env param helpers.
src/setup-codeql.test.ts	Uses EnvVar constants for Code Scanning PR env vars.
src/init.test.ts	Uses ActionsEnvVars constant for RUNNER_ENVIRONMENT.
src/autobuild.ts	Uses ActionsEnvVars.RUNNER_ENVIRONMENT instead of a raw string lookup.
src/config/remote-file.ts	Switches ActionsEnvVars import to environment.ts.
src/config/remote-file.test.ts	Switches ActionsEnvVars import to environment.ts.
lib/entry-points.js	Generated JS output change (not reviewed; diff content excluded by policy).

Review details

Files excluded by content exclusion policy (1)

• lib/entry-points.js

• Files reviewed: 11/12 changed files
• Comments generated: 1
• Review effort level: Low

[mario-campos]

Makes sense.

[mario-campos]

LGTM