Add pipeline value operations tests

[edoyango]

The tests covers all the operation classes in operations/{dask,numpy,xarray}/values.py. Some important changes:

• refactored xarray fillna to behave like numpy fillna
  • before, xarray fillna only filled nans, whereas numpy fillna also filled in positive and negative infinities.
• completed the implementation of dask fillna
  • This was raising a NotImplementedError, and just needed to add a missing arg in da.nan_to_num to make it work.
• use the Replace class instead of replace_value class from pyearthtool.data.transforms.mask as replace_value doesn't exist anymore.
• Renamed ForceNormalised operation to Clip since that matches the functions in dask/numpy/xarray
  • also refactored the classes to use the corresponding clip function
  • This is probably the most opinionated change here, happy to change back if it's a problem.
• fixed a problem in xarray.Derive where Derive.apply_func was also updating the input dataset.
• fixed a warning in pyearthtools.data.transforms.derive by replacing the deprecated Dataset.drop with Dataset.drop_vars

[coveralls]

Pull Request Test Coverage Report for Build 22118023831

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 151 of 152 (99.34%) changed or added relevant lines in 7 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+2.2%) to 67.196%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/data/src/pyearthtools/data/transforms/derive.py	7	8	87.5%

Totals
Change from base Build 20305027296:	2.2%
Covered Lines:	11036
Relevant Lines:	16061

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💛 - Coveralls

[nikeethr]

Thanks for the changes. Just had a minor comment (see above). Otherwise, it looks good.

appreciate the comments around deep copy and what they affect. Given that lot of applications of the pipeline can be memory hungry