Remove generated code when checking out a new branch

[blvrd]

Description

Generated code and mocks hang around when we change branches and can cause potential confusion when things don't work properly.

Reviewer notes

make clean might be too blunt of an instrument, since it forces us to re-build our binaries. Do we have a more lightweight command we should run instead, or just remove the pkg/gen folder along with mocks?

Setup

• scripts/install-post-checkout-hook
• try checking out another branch

Code Review Verification Steps

• Request review from a member of a different team.
• Have the Pivotal acceptance criteria been met for this change?

References

• Pivotal story for this change

[chrisgilmerproj]

I think this is a great start. I might also suggest having something in the Makefile that enforces that this hook is installed.

[codecov]

Codecov Report

Merging #2535 into master will decrease coverage by 0.2%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master   #2535     +/-   ##
========================================
- Coverage    60.1%   59.9%   -0.1%     
========================================
  Files         284     283      -1     
  Lines       15890   15844     -46     
========================================
- Hits         9535    9489     -46     
  Misses       5235    5235             
  Partials     1120    1120

Impacted Files	Coverage Δ
pkg/db/dbfmt/dbfmt.go

[blvrd]

@chrisgilmerproj updated based on your feedback. How should I communicate this kind of change? In #dp3-engineering?

[blvrd]

Closing since the # in the branch name is causing the build to break. Will open another PR.