Proto: prepare `per_block_vote` to allow multiple toggle votes

This MR is extracted from !5106 (closed) and depends on !5167 (merged).

This refactor the liquidity-baking-toggle-vote to easily add new toggle vote. An example can be found in !5106 (closed), see g.b.fefe/tezos@57888f0e

In the process, this MR add a non-mandatory option --liquidity-baking-toggle-vote to tezos-client bake for ....

Description

The MR is split in three parts, that can probably be reviewed and merged independently.

Refactor Liquidity_baking_repr

We first extract from Liquidity_baking_repr the type of toggle vote (e.g. LB_pass, ...) and the EMA code, they are moved in their onw module.

Patches:

• Proto/Per_block_vote: introduce Toggle_vote_repr

• Proto/Per_block_vote: introduce Toggle_vote_ema_repr

Prepare the protocol for new toggle votes

We then modify storage for allowing multiple vote, and update the record types for block header, block metadata and parametric constant, to replace the ad-hoc field for liquidity_baking by a record toggle_votes that can later be extended. This refactoring does not change the block binary representation.

• Proto/Per_block_vote: prepare storage for multiple vote
• Proto/Per_block_vote: prepare block metadata for multiple vote
• Proto/Per_block_vote: prepare constants for multiple vote
• Proto/Per_block_vote: prepare block header for multiple vote
• Proto/Per_block_vote: update testsuite

Prepare the baker

We then modify the baker code.

• Tests/Python: share toggle vote arguments
• Baker: prepare "Per_block_vote_file" for multiple votes
• Baker: prepare CLI for multiple votes
• Baker: add toggle votes options to "bake for"