[semantic] [typescript] No special highlighting for the 'this' parameter

[raptor494]

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.65.0
• OS Version: macOS 12.2.1

What's wrong:
The typescript semantic highlighter is currently highlighting the special 'this' parameter of function types/declarations the same as any other normal parameter.

Expectation:
I would expect the 'this' keyword to be highlighted as a keyword.

Possible Solutions:
Make the keyword token type "thisParameter" or add a modifier to it.

[a-tarasyuk]

It seems this is marked as keyword (for both cases classification("2020/original"))

TypeScript/tests/cases/fourslash/classifyThisParameter.ts

Lines 5 to 13 in 8002369

	const c = classification("original");
	verify.syntacticClassificationsAre(
	c.keyword("function"),
	c.identifier("f"),
	c.punctuation("("),
	c.keyword("this"),
	c.punctuation(")"),
	c.punctuation("{"),
	c.punctuation("}"));

@RyanCavanaugh Do we need to add a new semantic token thisParameter instead of keyword?