fix: check if cursor is on definition(#1042)

[shinohara-rin]

This pr addresses #1042 by checking if the cursor is on the same line as the definition of the symbol, if so, it will return references to the symbol instead.

[lukaszsamson]

Please add a test

[shinohara-rin]

Please add a test

Hi! I've added a test, please let me know if this is okay.

[lukaszsamson]

Suggested change

	test "find references if already on definition", %{server: server} do
	test "definition provider finds references when cursor already on definition", %{server: server} do

[lukaszsamson]

I wonder if this is the correct approach. microsoft/vscode#73081 and microsoft/vscode@1711f6e suggests that VSCode is doing that logic in the editor, not in language server. If the definition range contains cursor, it emits a second request for references. If that is indeed the case then addressing #1042 would solve the issue without reimplementing editor logic in the server

[lukaszsamson]

Yes, I confirmed that VSCode emits references request and displays Peek References when I return range from definitions, see this branch for PoC https://github.com/elixir-lsp/elixir-ls/tree/return-ranges