chore: add execProcess wrapper and refactor poetryUtils (Fixes #1239)

[karthiknadig]

This PR adds an execProcess wrapper to childProcess.apis.ts and refactors poetryUtils.ts to use it, improving testability.

Changes:

• Added execProcess function to src/common/childProcess.apis.ts as a wrapper around cp.exec with PYTHONUTF8 handling
• Refactored src/managers/poetry/poetryUtils.ts to use execProcess instead of direct child_process import
• Fixed a pre-existing regex bug in getPoetryVersion that didn't handle the space in Poetry 1.x version output format
• Added unit tests in poetryUtils.unit.test.ts demonstrating the mocking pattern for execProcess

Testing:

• All unit tests pass (660 passing)
• Lint passes with no errors

Note: This is a partial implementation of #1239. The acceptance criteria for auditing fs imports is deferred to a future PR to keep this change focused.

For #1239

[Copilot]

Pull request overview

This PR improves testability and consistency of child-process usage by introducing an execProcess() wrapper in src/common/childProcess.apis.ts and refactoring Poetry utilities to use it, while also fixing Poetry 1.x version parsing.

Changes:

• Added execProcess() wrapper around cp.exec() in src/common/childProcess.apis.ts.
• Refactored src/managers/poetry/poetryUtils.ts to use execProcess() instead of a direct child_process import + promisify.
• Added unit tests covering getPoetryVersion() parsing and demonstrating stubbing execProcess().

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/common/childProcess.apis.ts	Adds execProcess() wrapper to centralize cp.exec usage and improve mockability.
src/managers/poetry/poetryUtils.ts	Switches Poetry exec calls to the wrapper and adjusts version-regex parsing for Poetry 1.x output.
src/test/managers/poetry/poetryUtils.unit.test.ts	Adds unit tests that stub childProcess.apis.execProcess() and validate version parsing.

[Copilot]

execProcess is documented/typed to return stdout/stderr as strings, but cp.exec can return Buffers when callers pass encoding: 'buffer' | null in options. As written, a Buffer will flow through (it’s not nullish) and can break callers that do string operations (e.g. .trim()). Consider forcing encoding: 'utf8' (or converting Buffer→string before returning) to make the wrapper’s contract true and avoid runtime type mismatches.

Suggested change

	return {
	stdout: result.stdout ?? '',
	stderr: result.stderr ?? '',
	const rawStdout = result.stdout ?? '';
	const rawStderr = result.stderr ?? '';
	return {
	stdout: Buffer.isBuffer(rawStdout) ? rawStdout.toString('utf8') : rawStdout,
	stderr: Buffer.isBuffer(rawStderr) ? rawStderr.toString('utf8') : rawStderr,