Memory map the input file only when GDS compatiblity mode is not used

[vuule]

mmap is expensive on some systems and we can expect better performance with file reads when GDS is used, especially with compatibility mode.
This PR adds a source type that does not use mmap for host reads. This type is used when GDS and its compatibility mode are enabled.
file_source is now a base class for file-based input and only implements the device_read functions.
memory_mapped_source class implements the host reads through the memory mapped file.
direct_read_source is a newly implemented class that uses read for host reads, no mmap.
Selection is done in datasource::create based on cufile_config.

[codecov]

Codecov Report

Merging #7717 (b386930) into branch-0.19 (7871e7a) will increase coverage by 0.65%.
The diff coverage is n/a.

❗ Current head b386930 differs from pull request most recent head ca63a42. Consider uploading reports for the commit ca63a42 to get more accurate results

@@               Coverage Diff               @@
##           branch-0.19    #7717      +/-   ##
===============================================
+ Coverage        81.86%   82.52%   +0.65%     
===============================================
  Files              101      101              
  Lines            16884    17458     +574     
===============================================
+ Hits             13822    14407     +585     
+ Misses            3062     3051      -11     

Impacted Files	Coverage Δ
python/cudf/cudf/utils/gpu_utils.py	53.65% <0.00%> (-4.88%)	⬇️
python/cudf/cudf/core/column/lists.py	87.68% <0.00%> (-3.72%)	⬇️
python/cudf/cudf/core/column/decimal.py	92.95% <0.00%> (-1.92%)	⬇️
python/cudf/cudf/core/abc.py	87.23% <0.00%> (-1.14%)	⬇️
python/cudf/cudf/core/column/numerical.py	94.83% <0.00%> (-0.20%)	⬇️
python/cudf/cudf/core/column/column.py	87.61% <0.00%> (-0.15%)	⬇️
python/cudf/cudf/utils/utils.py	85.36% <0.00%> (-0.07%)	⬇️
python/cudf/cudf/io/feather.py	100.00% <0.00%> (ø)
python/cudf/cudf/utils/ioutils.py	78.71% <0.00%> (ø)
python/cudf/cudf/comm/serialize.py	0.00% <0.00%> (ø)
... and 45 more

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[vuule]

@gpucibot merge