Follow up on minimal target change to 1.8

[iloveeclipse]

Open TODO's from #2551

Created issues:

• Disabled tests summary ticket: Investigate tests disabled during transition to minimal 1.8 target #2758
• jclMin22.jar contains classes compiled against Java 21 #2580
• SourceMapper can't find source for inner classes for source compiled with Java 8 target #2754
• EclipseFileManager doesn't properly handle -extdirs for target 8 #2755
• jclMin1.8.jar is not complete for 1.8 JLS target tests #2756
• Nicer way to report "java version not supported" error in the IDE #2757
• Remove CompilerOptions.OPTION_InlineJsr & CompilerOptions.inlineJsrBytecode in 4.34 release #2759
• Remove obsoleted code in CompilerOptions #2760
• BatchCompilerTest.test248_jar_ref_in_jar fails on Windows #2766

Following questions wait for answering by others:

• [Stephan] Should this.currentProject.setOption(JavaCore.COMPILER_PB_RAW_TYPE_REFERENCE, JavaCore.IGNORE); be used in ConverterTestSetup.setUpJavaProject(String, String) ?
• [Stephan]: change on BatchCompilerTest.testBridgeMethodRetention This change probably conflicts with the purpose of this test, @srikanth-sankaran ?
• [Stephan] Change in ASTConverterTestAST8_2.test0612() caught me by surprise so I investigated:
  • the test implies to test AST at JLS8
  • using source from project Converter, Converter15, however, selects the AST level from the project.
    @srikanth-sankaran , @jarthana does it make any sense have such tests here? Shouldn't tests always sit in a test class corresponding to the used Converter* project, e.g., ASTConverterAST3Test?