Multisig TXs & Application Proposals: Metadata added to event emits

[SovereignAndrey]

Ticket(s):
Request for metadata to be included in subgraph, leads us to need to add it to the event emissions for:

1. Generic MultiSig Transaction Submission (covers AP Team & Charity Applications multisigs)
2. Normalized Endowment MultiSig Transaction Submission
3. Charity Applications Proposal Submission

Related to: AngelProtocolFinance/ap-subgraph#13

Explanation of the solution

• Adds metadata to the various event emits
• Standardizes Metadata as bytes for input type for functions & in storage field type used (previously Charity Applications used string & Normalized Endowments used bytes)

Instructions on making this work

• run yarn or yarn install to install npm dependencies
• run yarn test to verify all tests still pass