Add TensorYlm filter to GH and CSW evolutions

[nilsvu]

Proposed changes

Some cleanup of TensorYlm code, then adds GH and CSW TensorYlm filtering actions with caching. Last 3 commits are tiny improvements I found when trying to run spherical shells.

Upgrade instructions

Code review checklist

• The code is documented and the documentation renders correctly. Run
  make doc to generate the documentation locally into BUILD_DIR/docs/html.
  Then open index.html.
• The code follows the stylistic and code quality guidelines listed in the
  code review guide.
• The PR lists upgrade instructions and is labeled bugfix or
  new feature if appropriate.

Further comments

[nilsvu]

@kidder @nilsdeppe @wthrowe I switched to a base class implementation (only last commit changed). Let me know what you think!

[nilsvu]

Rebased on #7112 , so this PR should enable spherical shell filtering now.