dev/user-interface#45 Show associated participants on contributionView form

[braders]

Overview

Fixes dev/user-interface#45. Show associated participants on contributionView form.

As outlined on GitLab this introduces a way to navigate to participants from the contribution view:

This is done by reading the associated participants from the contribution line items using API4. If this is successfully reviewed I'll consider implementing similar functionality to list the purchased membership(s) on the view contribution screen. This should make the contribution view much more useful for CiviCRM users.

[civibot]

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[jaapjansma]

test this please

[jaapjansma]

• General standards
  • Explain (r-explain)
    • PASS : The goal/problem/solution have been adequately explained in the PR.
  • User impact (r-user)
    • PASS: The change would noticeably impact the user-experience (eg requiring retraining), but this has been addressed with a suitable transition/communication plan.
  • Documentation (r-doc)
    • PASS: The changes do not require documentation.
  • Run it (r-run)
    • PASS: We created an event with multiple participant registration and then we signed up on the live page and afterwards checked the created contribution.
• Developer standards
  • Technical impact (r-tech)
    • PASS: The change preserves compatibility with existing callers/code/downstream.
  • Code quality (r-code)
    • PASS: The functionality, purpose, and style of the code seems clear+sensible.
  • Maintainability (r-maint)
    • PASS: The change is trivial enough that it does not require tests.
  • Test results (r-test)
    • PASS: The test results are all-clear.

@eileenmcnaughton or @colemanw can one of you merge this PR? @bettydofling and I have reviewed this PR and we think this can be merged.