Description

Fix #3364, and other issues reported that were trying to access /service-worker.js.

This PR reworks the fs fallback check and skips it instead of failing with a security error if the URL results in a file access that is not allowed (ie out of workspace root for the moment, but later it could mean that it is present in a blocklist).

This change only applies when the user sets server.fsServe.strict to true

Additional context

The isFileAccessAllowed function may later contain more logic related to whitelist/blocklist so it is good that is already separated.

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.