Linter plugins: Various changes

[overlookmotel]

A short "shopping list" of potential changes/optimizations to JS linter plugins.

The first is a potential edge case bug. The rest are not urgent or important, but I just wanted to note them down somewhere.

• ExternalPluginStore should not contain plugin_names.
  • Plugin name to plugin ID should be resolved on a per-config basis
    (because 2 plugins can have same name but be different plugins).
  • Configs should store plugin IDs.
• Remove registered_plugin_paths from ExternalPluginStore. It's only needed while building configs, but never used again after that stage.
• external_rules_for_override in OxlintRules::override_rules could be a FixedBitSet?
  There probably aren't that many external rules, so FxHashMap<ExternalRuleId, AllowWarnDeny> is inefficient.
• Use only 1 Resolver for all nested configs - creating a Resolver is not cheap, and if there's only one, they'll all use the same cache.
• When JS plugin creates an error, code to get severity for rule is not optimal:
  • It has to search through external_rules to find the entry with RuleId
  • refactor(napi/oxlint): diagnostics communicate which rule via rule index, not rule ID #12482
• JS class for Context. refactor(napi/oxlint): introduce Context class #12440
• Recycle Context objects. perf(napi/oxlint): single Context object per rule #12475
• Add id property (rule name) to Context. feat(napi/oxlint): add id to Context #12480
• Improve perf of merging multiple visitors when many rules. perf(napi/oxlint): optimize compiling visitor #12472