Add support for "specialize" tag

[apendua]

Fixes #27387

This is an implementation proposal for @specialize JSDoc tag, which will allow specifying type arguments in JS files. For example if f has a type parameter T, the following JSDoc syntax:

let x = /** @specialize {number} */(f());

will be equivalent to TS:

let x = f<number>();

The tag can be also attached to any other parent node, e.g. assignment statement would also do:

/** @specialize {number} */
let x = f();

Currently, it is also possible to wrap type arguments with <...> as in /** @specialize <number> */,
if that's the preference. I couldn't make up my mind so I allowed both options for now.

The following expressions are also supported:

• tagged template expression
• "new" expression
• JSX element and self-closing tag

I am still planning to add more unit tests, e.g.

• check if "find all references" works
• test JSX syntax

Having said that, I've decided to open this PR early (as draft), because there are some open questions where I seek your advice:

• Is @specialize a good name for this tag? I was also considering @typeArgs, which I think would be a little bit cleaner in communicating its purpose, but I don't like the fact that it consists of two words, as so far there has been no precedence.
• One issue with @specialize is the fact that some people would prefer to spell it "specialise" and I am worried that it may cause confusion and typing errors in the future.

[typescript-bot]

Looks like you're introducing a change to the public API surface area. If this includes breaking changes, please document them on our wiki's API Breaking Changes page.

Also, please make sure @DanielRosenwasser and @RyanCavanaugh are aware of the changes, just as a heads up.

[typescript-bot]

The TypeScript team hasn't accepted the linked issue #27387. If you can get it accepted, this PR will have a better chance of being reviewed.

[Gerrit0]

Currently, it is also possible to wrap type arguments with <...> as in /** @specialize <number> */,
if that's the preference. I couldn't make up my mind so I allowed both options for now.

Please no. That isn't consistent with how any other type comments are parsed, the extra edge case doesn't just affect TS. @specialize {number} is consistent with @type