python,misc: Add check-symlinks hook to pre-commit

This hook checks that symlinks in the repo still point to valid
location.

Change-Id: I350760800406d9c003e81236af8248c6fc0a7359

.pre-commit-config.yaml

@@ -65,6 +65,7 @@ repos:
           - id: check-ast
           - id: check-case-conflict
           - id: check-merge-conflict
+          - id: check-symlinks
           - id: requirements-txt-fixer
     - repo: https://github.com/jumanjihouse/pre-commit-hook-yamlfmt
       rev: 0.2.3