Enable validation on root stac catalog

[jeremyh]

... and fix the missing field (needed for 1.0.0)!

For #320

[jeremyh]

Added missing validation for '/arrivals' catalog too.

[codecov]

Codecov Report

Merging #321 (6fd8994) into develop (52b2d09) will not change coverage.
The diff coverage is n/a.

❗ Current head 6fd8994 differs from pull request most recent head 7b2dd9b. Consider uploading reports for the commit 7b2dd9b to get more accurate results

@@           Coverage Diff            @@
##           develop     #321   +/-   ##
========================================
  Coverage    86.26%   86.26%           
========================================
  Files           25       25           
  Lines         3037     3037           
========================================
  Hits          2620     2620           
  Misses         417      417           

Impacted Files	Coverage Δ
cubedash/_stac.py	91.82% <ø> (ø)

---

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 52b2d09...7b2dd9b. Read the comment docs.