Add ects field in course form

[tobias-wiese]

Description

• Fixes Missing ETCS field #737

Reason for this PR

• see Missing ETCS field #737

Changes in this PR

• add the ects field analogous to the particitpants field

Type of change (remove all that don't apply)

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Manually tested all use cases this could alter

Test Configuration:

• OS: Windows

• Browser: Firefox

• Frontend: (remove all that don't apply)

  • Development build

• Backend: (remove all that don't apply)

  • deployed development build

Checklist: (remove all that don't apply)

• I added corresponding E2E tests (especially for bugfixes)
• I have performed a self-review of my own code
• My changes generate no new linting warnings or console warnings
• I have updated the CHANGELOG.md to include any changes made in this PR (add WIP to the top, if there is none already)