Add support for lazy-loading chunked xarray.Datasets with dask

[raphaelquast]

PR to improve handling of lazy-loaded Datasets with datashader.

• At the moment, this PR only handles 2D datasets plotted with m.set_shape.shade_raster()

TODOs

• check progress of Add fail-fast for datasets outside the visible extent holoviz/datashader#1345

[codecov]

Codecov Report

❌ Patch coverage is 30.00000% with 49 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.92%. Comparing base (db451fb) to head (6373e79).
⚠️ Report is 172 commits behind head on dev.

Files with missing lines	Patch %	Lines
eomaps/eomaps.py	29.03%	44 Missing ⚠️
eomaps/_data_manager.py	28.57%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #247      +/-   ##
==========================================
- Coverage   75.00%   74.92%   -0.08%     
==========================================
  Files          27       27              
  Lines       11853    11869      +16     
==========================================
+ Hits         8890     8893       +3     
- Misses       2963     2976      +13     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.