Make `ms-python.python` optional dependency

[T-256]

IF we could convert this file into typescript, then extension wouldn't need Python installation/activation on target system at all.
Currently Ruff extension needs python interpreter to start the server.

Originally posted by @T-256 in #443 (comment)

[T-256]

IMO, then we can also drop ms-python.python dependency since we don't need Python interpreter anymore.

ruff-vscode/src/extension.ts

Lines 161 to 164 in da06307

	"Python interpreter missing:\r\n" +
	"[Option 1] Select Python interpreter using the ms-python.python.\r\n" +
	`[Option 2] Set an interpreter using "${serverId}.interpreter" setting.\r\n` +
	"Please use Python 3.7 or greater.",

At there we could use ms-python.python as optional dep instead of mandatory dep.

[MichaReiser]

I'm not sure if removing the ms-python.python dependency is desired in the long term, or at least, not without implementing our own python selector.

I suspect that we'll soon need to call into Python from Ruff to discover the module search paths and possibly more. But we could make ms-python.python an optional dependency.

[charliermarsh]

Note that we have to call into Python if we want broad coverage for all system Pythons. Otherwise, there's no way to (completely) reliably get the path to the scripts directory.

[T-256]

I'm not sure if removing the ms-python.python dependency is desired in the long term, or at least, not without implementing our own python selector.

I suspect that we'll soon need to call into Python from Ruff to discover the module search paths and possibly more. But we could make ms-python.python an optional dependency.

Exactly, in addition I think, at this point Ruff itself has well defined its config selector (based on Extension settings which then fallbacks to pyproject.toml/ruff.toml either on workspace dir or its parent dir). IIUC, in this extension, Python discovery is mainly used to pass target version of python to ruff. we could rely on project.required-python or tool.ruff.target-version instead.

Otherwise, there's no way to (completely) reliably get the path to the scripts directory.

IIUC, we use scripts directory to find if Ruff binary available locally into that. This is good. What I suggested is to drop ms-python.python as hard dependency. which means if user already installed ms-python.python we can still get scripts directory and when not installed, this extension will lookup on $PATH only.

[T-256]

When ruff-lsp dropped, the only bundled required script would be find_ruff_binary_path.py.
This script will be used when ruff executable not discoverable in the PATH, so this script will locate common paths of given interpreter through ms-python.python extension:

ruff-vscode/src/common/server.ts

Lines 123 to 127 in 9da8dc2

	// Otherwise, we'll call a Python script that tries to locate a binary.
	let ruffBinaryPath: string | undefined;
	try {
	const stdout = await executeFile(settings.interpreter[0], [FIND_RUFF_BINARY_SCRIPT_PATH]);
	ruffBinaryPath = stdout.trim();

I think this isn't important step (since it mentioned as fallback method) and rarely used by users, So I think it can still work without requiring ms-python.python to be installed.