Add mask and mask! for DataFrames

[gabrieldansereau]

What the pull request does

Fixes #74. Adds additional mask and mask! functions to create presence-absence or abundance layers from DataFrames, similar to what we have for GBIFRecords.

TODO

• [x] Add mask and mask!
• [x] Keyword arguments
• [x] Unique coordinates for presence-absence
• [x] Tests
• [x] Example in documentation

Type of change

Please indicate the relevant option(s)

• [ ] :bug: Bug fix (non-breaking change which fixes an issue)
• [x] :sparkle: New feature (non-breaking change which adds functionality)
• [ ] :boom: Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] :book: This change requires a documentation update

Checklist

• [x] The changes are documented
  • [x] The docstrings of the different functions describe the arguments, purpose, and behavior
  • [x] There are examples in the documentation website
• [x] The changes are tested
• [x] The changes do not modify the behavior of the previously existing functions
  • If they do, please explain why and how in the introduction paragraph
• [x] For new contributors - my name and information are added to .zenodo.json
• [x] The Project.toml field version has been updated
  • Change the last number for a v0.0.x series release, a bug fix, or a performance improvement
  • Change the middle number for additional features that do not break the current test suite (unless you fix a bug in the test suite)
  • Change the first number for changes that break the current test suite

[codecov-io]

Codecov Report

Merging #79 (0d2a4eb) into master (1b4715f) will increase coverage by 0.40%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #79      +/-   ##
==========================================
+ Coverage   85.36%   85.77%   +0.40%     
==========================================
  Files          22       22              
  Lines         492      506      +14     
==========================================
+ Hits          420      434      +14     
  Misses         72       72              

Flag	Coverage Δ
unittests	85.77% <100.00%> (+0.40%)	:arrow_up:

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

Impacted Files	Coverage Δ
src/integrations/DataFrames.jl	98.27% <100.00%> (+0.54%)	:arrow_up:

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