Issue/option to download metadata once

[peterdudfield]

Pull Request

Description

Option to only download metadata once. As this is the same for eahc batch, no point downloading it again, if not needed

Bonus- some legacy data options

Fixes #

How Has This Been Tested?

normal UI, and tested with ML experiement

• [ ] Yes

If your changes affect data processing, have you plotted any changes? i.e. have you done a quick sanity check?

• [ ] Yes

Checklist:

• [ ] My code follows OCF's coding style guidelines
• [ ] I have performed a self-review of my own code
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have checked my code and corrected any misspellings

[codecov-commenter]

Codecov Report

Merging #710 (95fbf91) into main (f4f20cf) will decrease coverage by 0.25%. The diff coverage is 55.17%.

@@            Coverage Diff             @@
##             main     #710      +/-   ##
==========================================
- Coverage   93.25%   92.99%   -0.26%     
==========================================
  Files          48       48              
  Lines        3438     3454      +16     
==========================================
+ Hits         3206     3212       +6     
- Misses        232      242      +10     

Impacted Files	Coverage Δ
nowcasting_dataset/dataset/batch.py	88.81% <29.41%> (-5.43%)	:arrow_down:
nowcasting_dataset/filesystem/utils.py	97.59% <90.90%> (-1.16%)	:arrow_down:
...ng_dataset/data_sources/metadata/metadata_model.py	93.05% <100.00%> (ø)

:mega: Codecov can now indicate which changes are the most critical in Pull Requests. Learn more