Please support Java 21

[vpa1977]

I was able to compile procyon with Java 21 using release target 8, but have encountered some test failures:

• SwitchTests.testEnumSwitch - enum switch was decompiled as an ordinal switch
• ThirdPartyTests.testUnboxToNumber - decompiled code contains Constable, not Number.
• ThirdPartyTests.testLiteralAssignments - test specifies float numbers with excess precision, Java truncates those since 19.
• ThirdPartyTests.testOptimizedVariables, testSwitchKrakatau, testWhileLoopsKrakatau - decompiled variable does not match ('b' vs 'x')

[amy-b-cheng]

Also running into test failures for my application using Java 21 - getting this error:

Could not initialize class com.strobel.assembler.metadata.MetadataSystem java.lang.NoClassDefFoundError: Could not initialize class com.strobel.assembler.metadata.MetadataSystem