🐛 [#4772] Add migration to set select dataType to string

[stevenbal]

because Select components did not have a dataType set, formio tries to cast it to other types if possible, which causes issues when submitting the data to the backend. For that reason we set the value to string to avoid this unwanted normalization

TODO:

• upgrade formiobuilder once 🐛 [open-formulieren/open-forms#4772] Set select dataType to string formio-builder#194 is merged and released

Closes #4772

Changes

[Describe the changes here]

Checklist

Check off the items that are completed or not relevant.

• Impact on features

  • Checked copying a form
  • Checked import/export of a form
  • Config checks in the configuration overview admin page
  • Problem detection in the admin email digest is handled

• Release management

  • I have labelled the PR as "needs-backport" accordingly

• I have updated the translations assets (you do NOT need to provide translations)

  • Ran ./bin/makemessages_js.sh
  • Ran ./bin/compilemessages_js.sh

• Commit hygiene

  • Commit messages refer to the relevant Github issue
  • Commit messages explain the "why" of change, not the how

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.55%. Comparing base (b5daa22) to head (0fe69b3).
Report is 5 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4818   +/-   ##
=======================================
  Coverage   96.55%   96.55%           
=======================================
  Files         748      748           
  Lines       25417    25423    +6     
  Branches     3361     3362    +1     
=======================================
+ Hits        24542    24548    +6     
  Misses        610      610           
  Partials      265      265           

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[sergei-maertens]

Not backporting this PR, instead we'll backport the fix via the SDK