[Explorer/Outline] Add filter to show only exported members

[fuweichin]

In Outline view, I need a filter that "Show only exported members"(functions, constants or whatever), as if I were using a developer tool to inspect a library from a caller's perspective.

• For module js, the filter should find members modified by export keyword.
• For classic js (if supported), the filter should find function/variables exposed to global scope, those including top-level functions/vars. consider also eslint /* exported xxx */ and jsdoc /** @global */.
• For wasm/wat (if supported), the filter should find exports; see example https://beta.tourofdreamland.net/wasm-inspector/
• For lib files of other languages, this filter may find members that are public, public static or modified by other keyword of the same concept.

[jacekkopecky]

I would very much like that for typescript, please

[jacekkopecky]

I have a small proof of concept branch almost ready for submission/discussion at https://github.com/jacekkopecky/vscode/tree/outline-exports

[jacekkopecky]

@fuweichin I'd love your feedback at #329020

[fuweichin]

While my original idea is to add an option "Show only exported members" under Outline accordion header "..." (more options) or under a filter icon like the one in Timeline accordion header. The option may be set per-process or persistently, but it would be more convenient to set under the Outline accordion header "...", rather than in "Settings" panel or in settings.json.

For TypeScript / ES module, there are several cases to recognize a member as exported, see the export syntax.

export let/const/class/function/async function*/...
export {member1, member2 as a}
export {member1 as default}
export default member1

export * as member1 from "module-specifier";
export {member1} from "module-specifier"
export {default} from "module-specifier";
export * from "module-specifier";