Programming exercises: Add custom build scripts for local continuous integration

[laurenzfb]

Checklist

General

• I tested all changes and their related features with all corresponding user types on a test server.
• Language: I followed the guidelines for inclusive, diversity-sensitive, and appreciative language.
• I chose a title conforming to the naming conventions for pull requests.

Server

• Important: I implemented the changes with a very good performance and prevented too many (unnecessary) database calls.
• I followed the coding and design guidelines.
• I documented the Java code using JavaDoc style.

Motivation and Context

This PR builds on #7528 and adds basic support for custom build scripts in Local CI.

Description

Instructors can define script actions in the client during exercise creation which are then persisted in the database. During the set up of the build job container, these actions are retrieved for the build script.

Steps for Testing

Only test on TS3, TS5 or legacy TS11. Or test locally with LocalVC Local CI run configuration
Prerequisites:

• 1 Admin/Instructor

1. Open "Create Programming Exercise" form, fill all necessary fields and enable custom build plans
2. Click on the displayed action item
3. Add something in the editor that will not interfere with the testing tasks, e.g. echo "Hello World"
   
4. Create exercise
5. Wait till template and solution builds complete and verify results. (Template 0 out of 13, Solution 13 out of 13)

---

1. Do the same as above but now remove the action item
2. Add a new action item (don't change the code)
3. Create exercise
4. Verify that both builds fail

Testserver States

Note

These badges show the state of the test servers.
Green = Currently available, Red = Currently locked

Review Progress

Performance Review

• I (as a reviewer) confirm that the client changes (in particular related to REST calls and UI responsiveness) are implemented with a very good performance
• I (as a reviewer) confirm that the server changes (in particular related to database calls) are implemented with a very good performance

Code Review

• Code Review 1
• Code Review 2

Manual Tests

• Test 1
• Test 2

[JanaNF]

Manual tested on legacy_ts11. Worked as expected.

[valentin-boehm]

Tested on TS6, works as expected

[reschandreas]

tested locally, works as expected, code also lgtm

[florian-glombik]

Approving code

Quality and changes look good to me.