Summary:
This moves BCC to be a git repo in bazel. Note: we need to use it as a git module
because bcc has submodules.

Test Plan: existing

Reviewers: michelle, oazizi, vihang, #third_party_approvers

Reviewed By: vihang, #third_party_approvers

Differential Revision: https://phab.corp.pixielabs.ai/D8291

GitOrigin-RevId: c8017456e1ae60275906679195e7a862e7fde41d