feat: pass user args to `mvn` in `build-coatjava.sh`

Created by: c-dilks

This allows user arguments to be passed to the mvn command used in build-coatjava.sh.

I originally did this so one can run mvn multi-threaded, e.g.,

build-coatjava.sh -T 4  # runs with 4 threads

however, coatjava builds so quickly that this does not make any improvement whatsoever.

Maybe this PR will be useful someday though...

time build-coatjava.sh       # 70.39s user 3.69s system 335% cpu 22.071 total
time build-coatjava.sh       # 68.33s user 3.32s system 386% cpu 18.538 total

time build-coatjava.sh -T 1  # 64.44s user 3.39s system 339% cpu 19.979 total
time build-coatjava.sh -T 1  # 73.75s user 3.68s system 356% cpu 21.702 total

time build-coatjava.sh -T 2  # 76.67s user 3.77s system 501% cpu 16.045 total
time build-coatjava.sh -T 2  # 75.24s user 3.69s system 431% cpu 18.291 total

time build-coatjava.sh -T 4  # 74.28s user 4.00s system 486% cpu 16.075 total
time build-coatjava.sh -T 4  # 73.92s user 4.01s system 546% cpu 14.262 total

time build-coatjava.sh -T 8  # 68.79s user 3.97s system 517% cpu 14.059 total
time build-coatjava.sh -T 8  # 75.55s user 4.11s system 461% cpu 17.256 total