added backward compatibility mode if the new relocatedClasses parameter is missing

[jurgenvinju]

If a project depends on the Rascal project version with the new packager, which copies to a fresh folder instead of rewriting in-place in target/classes, and does not depend on rascal-maven-plugin which provides the fresh folder parameter relocatedClasses, then the maven plugin fails with a stack trace.

This fix runs the old in-place tpl rewriting in target/classes such that projects that do have the new rascal but not yet the new maven plugin, just keep working. Idea by @DavyLandman

Eventually switching to the new maven plugin has major benefits for the quality of the error messages in the IDE after you've types mvn install or mvn package once.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 46%. Comparing base (f09b3e3) to head (b9279e4).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##              main   #2609   +/-   ##
=======================================
- Coverage       46%     46%   -1%     
+ Complexity    6653    6652    -1     
=======================================
  Files          793     793           
  Lines        65697   65697           
  Branches      9839    9839           
=======================================
- Hits         30619   30606   -13     
- Misses       32719   32728    +9     
- Partials      2359    2363    +4     

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