Add verify scripts

[cbmarcum]

Verify scripts to download and verify release candidates and releases.

Mailing list discussion of changes.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.3781%. Comparing base (47d1b5b) to head (25137c9).
⚠️ Report is 23 commits behind head on master.

Additional details and impacted files

@@                Coverage Diff                 @@
##               master      #2414        +/-   ##
==================================================
- Coverage     66.4248%   66.3781%   -0.0467%     
- Complexity      29856      29876        +20     
==================================================
  Files            1386       1392         +6     
  Lines          116598     116799       +201     
  Branches        20632      20665        +33     
==================================================
+ Hits            77450      77529        +79     
- Misses          32804      32913       +109     
- Partials         6344       6357        +13     

see 82 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.