Announce supported capabilities

[predragnikolic]

LSP clients(like Sublime Text), won't send server requests if the server didn't announce support for those requests through capabilities.

Currently the Volar server only announces this capability:
https://github.com/johnsoncodehk/volar/blob/8733e9483389d9567525f0493b56697fe8f2c35a/packages/server/src/index.ts#L34-L36

But it should actually include lots of other capabilities.
Here is an example of what the Vetur server returns:

Note: I accidentally lowercased all the object keys :)

{
	"capabilities": {
		"foldingrangeprovider": true,
		"codeactionprovider": {
			"codeactionkinds": ["quickfix", "refactor", "refactor.extract", "refactor.inline", "refactor.rewrite", "source", "source.organizeimports"],
			"resolveprovider": true
		},
		"signaturehelpprovider": {
			"triggercharacters": ["("] 
		},
		"colorprovider": true,
		"semantictokensprovider": {
			"legend": {
				"tokenmodifiers": ["declaration", "static", "async", "readonly", "defaultlibrary", "local", "refvalue"],
				"tokentypes": ["class", "enum", "interface", "namespace", "typeparameter", "type", "parameter", "variable", "enummember", "property", "function", "method"]
			},
			"range": true,
			"full": true
		},
		"workspace": {
			"fileoperations": {
				"willrename": {
					"filters": [
						{
							"pattern": {
								"glob": "**/*.{ts,js,vue}"
							}
						}
					]
				}
			},
			"workspacefolders": {
				"changenotifications": true,
				"supported": true
			}
		},
		"completionprovider": {
			"triggercharacters": [".", ":", "<", "\"", "'", "/", "@", "*", " "],
			"resolveprovider": true
		},
		"hoverprovider": true,
		"executecommandprovider": {
			"commands": []
		},
		"documentlinkprovider": {
			"resolveprovider": false
		},
		"referencesprovider": true,
		"definitionprovider": true,
		"documenthighlightprovider": true,
		"textdocumentsync": {
			"didclose": {},
			"save": {},
			"didopen": {},
			"change": {
				"synckind": 2
			}
		},
		"documentformattingprovider": false,
		"documentsymbolprovider": true
	}
}

Additional context:

Even when I add a completion capability for completions:

	const result: vscode.InitializeResult = {
		capabilities: {
			textDocumentSync: vscode.TextDocumentSyncKind.Incremental,
			completionProvider: {
				triggerCharacters: ['.']
			}
		}
	};

When a LSP client sends a request to Volar,
Volar returns this error:

Client sends a request to volar:
:: --> LSP-volar textDocument/completion(5): {'position': {'line': 0, 'character': 0}, 'textDocument': {'uri': 'file:///home/predragnikolic/.config/sublime-text/Packages/LSP-volar/index.vue'}}

Volar sends back this:
:: <~~ LSP-volar 5: {'message': 'Unhandled method textDocument/completion', 'code': -32601}

So even when Volar has specified capabilities, the server still will not work with other LSP clients (just yet :). Do you have any idea why?

[johnsoncodehk]

You need to config which features should enable by initializationOptions in language client, because volar split language features to two TS language server to resolved request blocking. (#390)

See https://github.com/yaegassy/coc-volar/blob/master/src/index.ts#L129-L182.