Using TiffSlide instead of OpenSlide for a better deployment

[sarthakpati]

Fixes #54

Proposed Changes

• openslide is no longer a dependency
• data for unit tests has now been moved to Penn Box instead of Git LFS
• patch miner is now a separate function for end-to-end unit testing of histo pipeline
• requirements updated in setup.py

Checklist

• I have read the CONTRIBUTING guide
• My PR is based from the current GaNDLF master
• Non-breaking change (would not break existing functionality): please provide as many details as possible for any breaking change
• Function/class source code documentation added/updated
• Code has been blacked for style consistency
• If applicable, version information has been updated in GANDLF/version.py
• If adding a git submodule, add to list of exceptions for black styling in pyproject.toml file
• Usage documentation has been updated, if appropriate
• History has been updated, if appropriate
• Tests added or modified to cover the changes; if coverage is reduced, please give explanation

[sarthakpati]

@Geeks-Sid @grenkoca could one of you please take a look at this? Also, we would need to update the tests to test the histo inference mechanism, which was not covered by unit tests before.

[codecov]

Codecov Report

Merging #303 (5eaab71) into master (b638152) will increase coverage by 2.32%.
The diff coverage is 95.45%.

@@            Coverage Diff             @@
##           master     #303      +/-   ##
==========================================
+ Coverage   88.71%   91.03%   +2.32%     
==========================================
  Files          86       88       +2     
  Lines        4465     4561      +96     
==========================================
+ Hits         3961     4152     +191     
+ Misses        504      409      -95     

Flag	Coverage Δ
unittests	91.03% <95.45%> (+2.32%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
setup.py	0.00% <ø> (ø)
GANDLF/cli/patch_extraction.py	90.47% <90.47%> (ø)
testing/test_full.py	98.68% <93.75%> (-0.22%)	⬇️
GANDLF/compute/inference_loop.py	80.85% <95.12%> (+38.80%)	⬆️
GANDLF/cli/__init__.py	100.00% <100.00%> (ø)
GANDLF/data/inference_dataloader_histopath.py	100.00% <100.00%> (+100.00%)	⬆️

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[Geeks-Sid]

Let's address all first.