Use rmm::device_uvector in place of rmm::device_vector for ORC reader/writer and cudf::io::column_buffer

[vuule]

Issue #7287

Replaces device_vector with device_uvector and device_span. Because device_uvector does not have a default constructor, some additional changes were required for device_uvector data members.

Performance impact: this change makes a measurable difference in reader benchmarks. Most string column cases are sped up around 5%, with other cases having a measurable, but less consistent improvement.

[codecov]

Codecov Report

Merging #7614 (12b52d1) into branch-0.19 (7871e7a) will increase coverage by 0.52%.
The diff coverage is 93.75%.

❗ Current head 12b52d1 differs from pull request most recent head 63228f6. Consider uploading reports for the commit 63228f6 to get more accurate results

@@               Coverage Diff               @@
##           branch-0.19    #7614      +/-   ##
===============================================
+ Coverage        81.86%   82.39%   +0.52%     
===============================================
  Files              101      101              
  Lines            16884    17350     +466     
===============================================
+ Hits             13822    14295     +473     
+ Misses            3062     3055       -7     

Impacted Files	Coverage Δ
python/cudf/cudf/core/index.py	93.34% <ø> (+0.48%)	⬆️
python/cudf/cudf/core/column/numerical.py	94.83% <87.50%> (-0.20%)	⬇️
python/cudf/cudf/core/frame.py	89.09% <89.47%> (+0.08%)	⬆️
python/cudf/cudf/core/column/column.py	87.86% <90.00%> (+0.10%)	⬆️
python/cudf/cudf/core/column/decimal.py	92.75% <90.32%> (-2.12%)	⬇️
python/cudf/cudf/core/dataframe.py	90.58% <95.65%> (+0.11%)	⬆️
python/cudf/cudf/core/series.py	91.57% <95.83%> (+0.79%)	⬆️
python/cudf/cudf/core/column/categorical.py	91.97% <100.00%> (+0.58%)	⬆️
python/cudf/cudf/core/column/datetime.py	89.63% <100.00%> (+0.54%)	⬆️
python/cudf/cudf/core/column/string.py	86.76% <100.00%> (+0.26%)	⬆️
... and 58 more

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[vuule]

Rerun tests

[vuule]

@gpucibot merge