Allow open date range in dataset search

[Ariana-B]

Reason for this pull request

See #1217

Proposed changes

• Update Lark grammar to recognise '<' and '>' in search expression

• Treat open ranges as a range from specified lower bound to today or from unix epoch to specified upper bound

• Closes Support open-ended ranges in dataset search #1217

• Tests added / passed

• Fully documented, including docs/about/whats_new.rst for all changes

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📚 Documentation preview 📚: https://datacube-core--1439.org.readthedocs.build/en/1439/

[codecov]

Codecov Report

Patch coverage: 33.33% and project coverage change: -0.08 ⚠️

Comparison is base (df7f48f) 91.84% compared to head (18c1f2c) 91.76%.

❗ Current head 18c1f2c differs from pull request most recent head 11e9dc6. Consider uploading reports for the commit 11e9dc6 to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1439      +/-   ##
===========================================
- Coverage    91.84%   91.76%   -0.08%     
===========================================
  Files          132      132              
  Lines        14466    14483      +17     
===========================================
+ Hits         13286    13291       +5     
- Misses        1180     1192      +12     

Impacted Files	Coverage Δ
datacube/ui/click.py	84.04% <ø> (ø)
datacube/api/query.py	90.27% <11.11%> (-3.45%)	⬇️
datacube/ui/expression.py	74.07% <55.55%> (-4.19%)	⬇️

... and 2 files with indirect coverage changes

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[robbibt]

Hey @Ariana-B, this will be so useful! There's a stale/wontfix issue here from way back in 2017 proposing something similar - great to see it finally implemented!

Any chance of getting this documented on the ODC user guide dc.load API page so that future users will know about the functionality when they try to load datacube data? This feels like the kind of feature that might be easy to miss without being mentioned in the docs (that page really should mention that you can specify just a single value like "2023" as well).
https://datacube-core.readthedocs.io/en/latest/api/indexed-data/generate/datacube.Datacube.load.html#datacube.Datacube.load

[Ariana-B]

Hey @robbibt, this PR doesn't affect dc.load, but happy to raise another PR!