observer: Revise policy type names

[lumtis]

Context: #912 (comment)

Make a walkthrough of the different policy types and rename them appropriately depending on their usage.

[lumtis]

Did a walkthrough of the types:

• Policy_Type_stop_inbound_cctx: can update permission flags to disable inbound and outbound in cctx.

Should be renamed

• Policy_Type_deploy_fungible_coin - can:
  • Whitelist ERC20
  • Deploy foreign coin
  • Remove foreign coin
  • Update system contract
  • Pause ZRC20
  • Update ZRC20 bytecode
  • Update withdraw fees

Should be renamed

• Policy_Type_update_client_params - update core params, looks up-to-date although client_params could be renamed into core_params

• Policy_Type_update_keygen_block - update TSS address and Keygen

Should be renamed

• Policy_Type_out_tx_tracker - Add to out tx tracker or remove from out tx tracker, looks up-to-date

• Policy_Type_add_observer - Add observer, looks up-to-date

We might also want to merge some of the rule to simplify the authorization structure.

cc @zeta-chain/protocol-engineering

[fadeev]

Create a doc with all the privileged message types. Depending on how complex this ends up being, we might consolidate the roles.

[lumtis]

Update: doc set up on Notion: Engineering / Protocol Docs / Observer Policy Types

[fadeev]

https://www.notion.so/zetachain/Observer-Policy-Types-4e501dd64dfc460180a361f9b8507310