Terminal suggest: Fine tune kind and icons coming from fig completions

[Tyriar]

Currently the kind assigned to fig items is a little simple:

vscode/extensions/terminal-suggest/src/terminalSuggestMain.ts

Lines 325 to 333 in b888f04

	if (parsedArguments.suggestionFlags & SuggestionFlag.Args) {
	await addSuggestions(parsedArguments.currentArg?.suggestions, vscode.TerminalCompletionItemKind.Argument, parsedArguments);
	}
	if (parsedArguments.suggestionFlags & SuggestionFlag.Subcommands) {
	await addSuggestions(parsedArguments.completionObj.subcommands, vscode.TerminalCompletionItemKind.Method);
	}
	if (parsedArguments.suggestionFlags & SuggestionFlag.Options) {
	await addSuggestions(parsedArguments.completionObj.options, vscode.TerminalCompletionItemKind.Flag);
	}

Here are some things we want to achieve:

• Git branch, tag, stash icons for their respective completions
• Differentiate flags (no value) and options (with value) Differentiate flag and option completion types #241392
• Map any icon specified by fig to the right type

We might need to explore an upstream change to the fig spec to indicate a generic kind for the completion, rather than just an icon.

Related: #239706

[meganrogge]

I think the remaining thing here is to support icons coming from the extension? Maybe just a string that has to map to a codicon? I don't think we want to add a ton of specific kinds

[Tyriar]

@meganrogge that, plus figuring out the best way of mapping fig completion types with our icons. For example checking detail/documentation if it's = "Branch", or checking their icon URI and having our own mapping. They're both not super robust, but we could use the spec unit tests to prevent regressions when we update git.ts for example.