Feature request - Expand JS SDK support for core transaction types

[jurevans]

Copied from namada-net/namada-interface#2000 opened by @gavinly

Governance

• InitProposal

Public Goods Funding (PGF) transactions

• ResignSteward
• UpdateStewardCommission

Validator management

• BecomeValidator (low priority)
• DeactivateValidator
• ReactivateValidator
• Unjail (low priority)
• CommissionChange
• MetadataChange

Multisigs: High-Level Helper for Account Updates (similar to namada update-account)

A higher-level helper function (eg. sdk.tx.buildUpdateAccount(...)) would simplify common account update operations

• Adding or removing public keys associated with an account
• Setting or updating the signing threshold for multi-signature accounts