Isolate optimizer step logic to the PrecisionPlugin

[carmocca]

What does this PR do?

• Run the closure to PrecisionPlugin.pre_optimizer_step whenever possible. This will make the transition to only allowing the step in the PrecisionPlugin easier.
• Improve unsupported LBFGS checks
• Improve unsupported backward skipping checks.

Part of #9287

Does your PR introduce any breaking changes? If yes, please list them.

None in stable API

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[codecov]

Codecov Report

Merging #10029 (265189e) into master (2ed92ec) will decrease coverage by 0%.
The diff coverage is 60%.

@@           Coverage Diff           @@
##           master   #10029   +/-   ##
=======================================
- Coverage      93%      93%   -0%     
=======================================
  Files         180      180           
  Lines       15892    15909   +17     
=======================================
+ Hits        14722    14725    +3     
- Misses       1170     1184   +14     

[tchaton]

LGTM !