[master] Add `clear` patch field operation and provide `max_ops` property to patch fields

[codecov-io]

Codecov Report

Merging #897 into master will increase coverage by 2%. The diff coverage is 92.4%.

@@           Coverage Diff           @@
##           master    #897    +/-   ##
=======================================
+ Coverage    92.6%   94.5%    +2%     
=======================================
  Files         333     333            
  Lines       29371   29374     +3     
=======================================
+ Hits        27177   27739   +562     
+ Misses       2194    1635   -559

Impacted Files	Coverage Δ
guillotina/contrib/email_validation/__init__.py	100% <ø> (ø)	:arrow_up:
guillotina/response.py	87.9% <100%> (+0.1%)	:arrow_up:
guillotina/renderers.py	86.9% <100%> (ø)	:arrow_up:
guillotina/contrib/dbusers/register_user.py	100% <100%> (ø)	:arrow_up:
guillotina/contrib/email_validation/utility.py	82.8% <66.7%> (-0.6%)	:arrow_down:
guillotina/db/transaction.py	90.4% <0%> (+1%)	:arrow_up:
guillotina/tests/mocks.py	89.9% <0%> (+1.6%)	:arrow_up:
guillotina/contrib/dbusers/services/users.py	88.8% <0%> (+1.7%)	:arrow_up:
guillotina/utils/misc.py	79.5% <0%> (+1.8%)	:arrow_up:
guillotina/contrib/dbusers/services/groups.py	95.6% <0%> (+2.3%)	:arrow_up:
... and 16 more

[vangheem]

It should be increased. Everything is covered and I added extra tests for things not covered. I can check later but maybe the report is wrong.

[bloodbare]

It should be increased. Everything is covered and I added extra tests for things not covered. I can check later but maybe the report is wrong.

Thanks why I was commenting, I saw a red coverage but I can't see in code why

[vangheem]

I don't understand the report. If you look at https://codecov.io/gh/plone/guillotina/pull/897/diff -- with what I touched, I should have better coverage...

[vangheem]

I wonder if it does a bad job handling cherry pick? I'm merging. The reports everywhere on codecov do not make sense.