WIP: Parse operation only once in prevalidator

Fixes #1510 (closed)

Todo

• Add a commit that change the type of pending ops and parse only on arrived and on injection
• Fix unit testing
• Add tezt test that inject unparsable operation
• Add rpc regression test that inject unparsable operation

Context

This MR aims to remove multiple parsing of operation in prevalidator.ml by parsing each operation only once.

Manually testing the MR

Run the following command to run the new test dune exec tezt/tests/main.exe -- parse

Checklist

• n/a Document the interface of any function added or modified (see the coding guidelines)
• n/a Document any change to the user interface, including configuration parameters (see node configuration)
• n/a Provide automatic testing (see the testing guide).
• n/a For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, the Development Version section of CHANGES.md for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR