Modify autocomplete for ManagedGroups

[amstilp]

• Optionally allow the user to specify that ManagedGroupAutocomplete should only return groups that are managed by the app using a forwarded value.
• Modify the GroupGroupMembershipForm to pass only_managed_by_app forwarded value to autocomplete for the parent group.
• Modify the GroupAccountMembershipForm to pass only_managed_by_app forwarded value to autocomplete for the group.

This allows child groups to be added as members of another group, and also allows workspaces to be shared with them.

Closes #399

[codecov[bot]]

Codecov Report

Merging #412 (3a1975c) into main (649bce5) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #412   +/-   ##
=======================================
  Coverage   99.82%   99.82%           
=======================================
  Files         121      121           
  Lines       22872    22882   +10     
=======================================
+ Hits        22833    22843   +10     
  Misses         39       39           

Files	Coverage Δ
anvil_consortium_manager/__init__.py	100.00% <100.00%> (ø)
anvil_consortium_manager/forms.py	100.00% <100.00%> (ø)
anvil_consortium_manager/tests/test_views.py	99.92% <100.00%> (+<0.01%)	:arrow_up:
anvil_consortium_manager/views.py	99.86% <100.00%> (+<0.01%)	:arrow_up:

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