feat: Notify Invalid RegExp Patterns

[aedenmurray]

This PR allows users to be notified when an invalid regex pattern is encountered.
This is useful if a JSON schema is published that contains patterns that are not supported by new RegExp().
For example, as of time of writing, the version pattern for the composer.json schema includes a possessive quantifier (*+) that is not supported by JavaScript (see composer.json schema definition).

[aedenmurray]

@microsoft-github-policy-service agree company="Shadowscape, Inc."

[aeschli]

The JSON schema spec says that regexes must match the Regular Expression specification from JavaScript. https://json-schema.org/understanding-json-schema/reference/regular_expressions. So likely this is an issue with the composer.json

The error should be shown on the schema document and not on the document that is being validated.
I would say it's correct to ignore such regexes.
If we want to show a problem, then it would be a warning, and the message needs to be clear that this is an issue of the schema.

Something like 'Unable to validate value. Pattern {0} provided by the schema is not supported.'

[aedenmurray]

Thanks @aeschli!
You are correct - this is an issue with composer.json.
However, the current implementation attempts to blame the user, which is misleading:

I agree with the sentiment that invalid patterns should be ignored.
I have updated the PR to match.