uv3 migration tool class path setup

There are multiple issues with the migrateClasspath setup for v3 migration.

There are two uses of the classpath.

• One is for decompiling the v2 compiled classes, when migrating from classes - roots.
• The other is for (optional) compiling of the resulting converted source. These is done for the use case where the v2 classes were in JARs or PEARs, and the result of the conversion is new versions of these JARs or PEARs with converted JCas classes.

The classpath passed for migrateClasspath should be the v2 classpath needed for decompiling the v2 JCas classes. When recompiling, the classpath for v3 uimaj-core is prepended.

migrateClasspath is temporarily augmented when migrating PEAR files, by prepending any PEAR classpath specs.
A separate Jira improved the migrateClasspath to permit the Java style of classpath specs using a trailing wildcard .

Changes needed:

• if the migrateClasspath argument is not set:
  • if migrating from classes roots, treat this as an error; migrateClasspath is required in order to properly decompile.
    • Add a note that this classpath must include the classes being migrated, because they are read from that classpath.
  • If migrating from sources roots, if the migrateClasspath is not set, substitute the application classpath, with a warning.

• for compiling:
  1. do the PEAR prepending if the source came from a pear.
  2. prepend at the very front, the uimaj-core-v3 (or the app classpath).