forward upgrade utils

[SkafteNicki]

What does this PR do?

Follow up to #984

• Change the default of the new full_state_update property to None. It will still works as full_state_update=True (old behavior) but a warning will be given to the user that they should consider setting the flag.
• Add utility tool for checking if it is save to set the flag
• Adds some tests

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

[codecov]

Codecov Report

Merging #1033 (460aa1f) into master (a009bed) will decrease coverage by 0%.
The diff coverage is 93%.

@@          Coverage Diff           @@
##           master   #1033   +/-   ##
======================================
- Coverage      95%     95%   -0%     
======================================
  Files         181     181           
  Lines        7882    7937   +55     
======================================
+ Hits         7474    7526   +52     
- Misses        408     411    +3