Gridded product metadata attributes

[mhidas]

Add code version, code github URL, and source file download/OPENDAP URLs in global attributes of the gridded product. (as done in #78 and #96 for the other two products).

Also limited the global attributes copied from the input file to an specified list (rather than everything).

[codecov[bot]]

Codecov Report

Merging #106 into master will decrease coverage by 0.66%. The diff coverage is 0%.

@@            Coverage Diff             @@
##           master     #106      +/-   ##
==========================================
- Coverage   65.18%   64.51%   -0.67%     
==========================================
  Files           7        7              
  Lines         965      975      +10     
  Branches      151      154       +3     
==========================================
  Hits          629      629              
- Misses        309      319      +10     
  Partials       27       27

Impacted Files	Coverage Δ
...odntools/timeseries_products/gridded_timeseries.py	0% <0%> (ø)	:arrow_up:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update b6b2f70...7c4ece1. Read the comment docs.

[diodon]

all good!