fix(collections): add migration for collection metadata

[ReenigneArcher]

Description

This PR adds a migration option to unlock fields locked for collections prior to v0.3.0. It only unlocks fields for collections with a theme song.

Screenshot

Issues Fixed or Closed

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update (updates to dependencies)
• Documentation update (changes to documentation)
• Repository update (changes to repository files, e.g. .github/...)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

Branch Updates

LizardByte requires that branches be up-to-date before merging. This means that after any PR is merged, this branch
must be updated before it can be merged. You must also
Allow edits from maintainers.

• I want maintainers to keep my branch updated

[codecov]

Codecov Report

Attention: 6 lines in your changes are missing coverage. Please review.

Comparison is base (b0d8452) 70.14% compared to head (857de8c) 70.10%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #345      +/-   ##
==========================================
- Coverage   70.14%   70.10%   -0.04%     
==========================================
  Files          12       12              
  Lines         988     1007      +19     
==========================================
+ Hits          693      706      +13     
- Misses        295      301       +6     

Flag	Coverage Δ
Linux	70.10% <68.42%> (-0.04%)	⬇️
Windows	69.91% <68.42%> (-0.03%)	⬇️
macOS	69.91% <68.42%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
Contents/Code/default_prefs.py	100.00% <ø> (ø)
Contents/Code/migration_helper.py	82.17% <68.42%> (-3.19%)	⬇️