Migrate SWT suites to JUnit 5

[akurtakov]

First towards being able to move unit tests to JUnit 5.

[github-actions]

Test Results

   533 files  +24     533 suites  +24   28m 21s ⏱️ + 19m 45s
 4 363 tests +55   4 348 ✅ +52   15 💤 +4  0 ❌  - 1 
16 595 runs  +19  16 485 ✅ +18  110 💤 +2  0 ❌  - 1 

Results for commit f8cfc95. ± Comparison against base commit 9440140.

This pull request removes 2 and adds 57 tests. Note that renamed tests count towards both.

org.eclipse.swt.tests.junit.Test_org_eclipse_swt_widgets_Display ‑ test_setCursorLocationII
org.eclipse.swt.tests.junit.Test_org_eclipse_swt_widgets_Display ‑ test_setCursorLocationLorg_eclipse_swt_graphics_Point

AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicASCII_dollarSign
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicASCII_emptyString
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicASCII_letterA
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicASCII_letters
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16LE_null
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16_AsciiLetters
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16_Asciiletter
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16_LotsOfLetters
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16_letter
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16_letters
…

♻️ This comment has been updated with latest results.

[akurtakov]

Test results are stable but build is marked unstable due to warnings which change +/-10 for each build(no idea why for now). Will fire an I-build to verify that nightly tests will not break.