Add replacements column support for Java replaceNulls [skip ci]

[jlowe]

Adds Java bindings for cudf::replace_nulls with a columnar replacement parameter.

[codecov]

Codecov Report

Merging #7750 (fa1e294) into branch-0.19 (ccc28d5) will increase coverage by 0.38%.
The diff coverage is n/a.

❗ Current head fa1e294 differs from pull request most recent head a3fdbd6. Consider uploading reports for the commit a3fdbd6 to get more accurate results

@@               Coverage Diff               @@
##           branch-0.19    #7750      +/-   ##
===============================================
+ Coverage        82.13%   82.52%   +0.38%     
===============================================
  Files              101      101              
  Lines            17096    17458     +362     
===============================================
+ Hits             14042    14407     +365     
+ Misses            3054     3051       -3     

Impacted Files	Coverage Δ
python/cudf/cudf/utils/gpu_utils.py	53.65% <0.00%> (-4.88%)	⬇️
python/cudf/cudf/core/abc.py	87.23% <0.00%> (-1.14%)	⬇️
python/cudf/cudf/io/feather.py	100.00% <0.00%> (ø)
python/cudf/cudf/comm/serialize.py	0.00% <0.00%> (ø)
python/cudf/cudf/_fuzz_testing/io.py	0.00% <0.00%> (ø)
python/cudf/cudf/core/column/struct.py	100.00% <0.00%> (ø)
python/dask_cudf/dask_cudf/_version.py	0.00% <0.00%> (ø)
python/cudf/cudf/_fuzz_testing/fuzzer.py	0.00% <0.00%> (ø)
python/cudf/cudf/utils/hash_vocab_utils.py	100.00% <0.00%> (ø)
python/dask_cudf/dask_cudf/io/tests/test_csv.py	100.00% <0.00%> (ø)
... and 40 more

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[jlowe]

rerun tests

[jlowe]

@gpucibot merge