Support Git pre-push hook generation to location defined by core.hooksPath

[bgorkowy]

Instead of spotlessInstallGitPrePushHook always writing to .git/hooks/pre-push, the task asks Git to resolve hooks/pre-push, so it respects core.hooksPath when configured, as requested in #2853 .
This uses ExecOperations to call git directly for the config, you have to decide if it is ok in this action - previous implementation operates only on the file api.

Changes

• Resolve the effective hook path during task execution using Git.
• Validate the destination before installation. The task skips unsupported repositories, hook directories outside the project, and destinations where pre-push is a directory or symbolic link.
• Preserve the existing behavior for repositories using the default .git/hooks directory.
• Add integration tests for the default location, a custom core.hooksPath, existing hooks, and unsupported destinations.