Improve duplicate clinit removal

[niloc132]

Explore comma expression contents when finding class initializers, and mark them as seen to avoid their inclusion later in method bodies. Also improved try block handling when there are no catches or finallys, and left notes for how this can be later improved when control flow is more structured (#10248, #10381)

Moved this pass into the main JS optimization loop - inlining methods tends to produce grouped clinits, and clinit removal can leave behind dead code that needs to be simplified away. In some cases, clinit removal make also make a method eligible for inlining.

This code previously had no tests, so added a test class, and improved the JS OptimizerTestBase to allow for minor changes (newlines, etc) between input and expected contents, as well as asserting for "no change" when appropriate. This more closely mirrors the Java version of this test base.

Also cleans up some "XO" references ("eXactly Once") in favor of "clinit" as referenced elsewhere.

Fixes #9731

[niloc132]

Marked as draft for now, some additional tests are required, and some text blocks can be used in place of separate string vararg params. Showcase improves by about 0.1%, or about 300 bytes over 300-400kb permutations.