Doc: add new entry for (pipelined) validation of blocks and operations to the economic protocol documentation

(Contributes to #3162 (closed), fixes #3111 (closed), #3937 (closed))

Context

This MR adds a new entry for the documentation of the economic protocol focusing on (pipelined) validation of operations and blocks. It serves also as a new home for a few concepts that were sprinkled around in the docs: validation passes, validation modes, and the semantics of batches.

This MR: pipelined validation up-to Katmandu

• document operations and validation passes;
• document manager operations properly and thoroughly;
• document and explain the semantic of manager operation batches' semantics (fixes #3111 (closed));
• document pipelined validation of manager operations;
• document block validation and validation modes;
• backport to Kathmandu documentation.
• harmonize manager operations precheck and plugin documentation entries for Kathmandu wrt validation section.
• integrate consensus keys operations in the operations list for Lima/Alpha.
• #3937 (closed) document the increased paid storage manager operation.

What this MR doesn't do (See #3162 (closed) and #3921 (closed) for context)

• document non-pipelined validation of non-manager operations for Kathmandu #3162 (closed)
• harmonize manager operations precheck and plugin documentation entries in Alpha and Lima after Pipelining phase 2 is fully implemented #3938 (closed)
• update pipelined validation of voting (!5828 (merged)), anonymous (!5849 (merged)) and consensus ops (!5927 (merged)) for Alpha and Lima #3921 (closed)
• pipelined block validation modulo Lima.

These are being/will be implemented in follow-up MR !6530 (closed)

Other follow ups added as TODOs

• #3936 (closed) integrate the rest of the consensus keys docs from the Changelog
• #3937 (closed) document increased paid storage manager operation
• #3914 (closed) integrate details from protocol-specific block content in the new "blocks and ops" protocol entry.
• #3916 (closed) document TORU operations in the new entry
• #3915 (closed) list failing noops in the new doc entry, integrating the existing documentation