BREAKING CHANGE:
[utils] setsprogram = null forgetParserServices(context, true).
[typescript-estree] disallowserrorOnTypeScriptSyntacticAndSemanticIssues ifproject not provided

PR Checklist

• Addresses an existing open issue:fixesEnhancement: Remove 2 year old backwards compatibility check from getParserServices #5508
• That issue was marked asaccepting prs
• Steps inCONTRIBUTING.md were taken

Overview

A few years ago I experimented with leveraging TS's unused variable diagnostics to power a lint rule. As this diagnostic is "single-file", I added the ability for the parser to generate a program in "isolated" mode (i.e. noparserOptions.project required and types/diagnostics only produced for the single file) as well as the ability for plugins to interact with this program.

However this approach had some major drawbacks:

1. calculating diagnostics in TS is slow - so the lint rule was slow as there's no way to tell TS to calculate specific diagnostics.
2. the isolated types are completely useless because in most modules so many types are seeded from imports.

We never bothered going back to cleanup this work (until now).

This PR:

1. updates the parser so that it only works withts.SourceFiles if we're not doing type-aware linting.
   • this should have the added bonus of speeding the parser up for non-type-aware runs as we're not going through the heavy process of creating a program!
2. updates thegetParserServices util as appropriate
   • Note: I left the ability to consume parser services without type info because the node maps can be useful in some situations, or sometimes it's useful to consume compiler options if provided.
3. removes thesemantic-diagnostics-enabled test because it's a test that we don't get any value out of - it's just emitting TS errors which might change from version to version
4. only allowserrorOnTypeScriptSyntacticAndSemanticIssues if we have full type info.
   • This is because TS doesn't compute a lot of diagnostics without a program!