Add rollForward note in README, improve proxy health check in e2e tests and bump version to v5.3.0

[priyagupta108]

Description:

• Adds a note in the global-json-file section of the README documenting support for latest* variants of the rollForward policy (latestPatch, latestFeature, latestMinor, and latestMajor) in global.json.
• Adds a health check for the squid proxy container in the e2e tests workflow.
• Bumps package version to 5.3.0.

Related issue:
#448

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.

[Copilot]

Pull request overview

This PR updates the action’s documentation to clarify support for global.json rollForward policies, and also updates the package version metadata.

Changes:

• Add a README note stating that global.json rollForward supports latestPatch, latestFeature, latestMinor, and latestMajor.
• Bump package.json and package-lock.json version from 5.0.1 to 5.3.0.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
README.md	Adds documentation note about latest* rollForward support in global.json.
package.json	Updates the package version to 5.3.0.
package-lock.json	Updates lockfile metadata to match the new package version.

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