Add command line parser and entry points

[ting-yuan]

So that it can be invoked like:

java -cp <KSP and Kotlin library classpath> \
      com.google.devtools.ksp.cmdline.KSPJvmMain \
      -module-name=MyModule \
      -source-roots /path/to/source/roots \
      -kotlin-output-dir=/path/to/output/Kotlin \
      -java-output-dir /path/to/output/Kotlin \
      ...
      /path/to/processor.jar

Help message can be printed with -h or --help:

Available options:

*   -module-name=String
*   -source-roots=List<File>
    -common-source-roots=List<File>
    -libraries=List<File>
    -processor-options=Map<String, String>
...
where:
 * is required
 List is colon separated. E.g., arg1:arg2:arg3
 Map is in the form key1=value1:key2=value2

[neetopia]

any context on the compiler version update?

[ting-yuan]

Bumped to be used with the latest KSP.

[neetopia]

substringAfter?