Rename message => blob where applicable

[rootulp]

Context

#978 (comment)

Problem

The codebase currently uses the previous term message in a number of locations where blob is more accurate after #978 merged.

Proposal

On a case by base basis, rename message, msg, or data => blob. Note: Cosmos SDK messages should still be called messages. We should only rename instances that refer to the data a user submits to be published to the Celestia blockchain.

• Update code: chore: rename message => blob #1060
• Update ADRs: docs: rename message => blob in ADRs #1531
• Update specs: specs: rename message => blob #1532

[rootulp]

Also instances of data may need to be renamed to blob. Ex:

celestia-app/app/process_proposal.go

Lines 26 to 27 in b81723b

	// - the commitment in each PFB should match that of its corresponding data
	// - there should be no unpaid-for data

[rootulp]

Will do this soon because it's leaking into other unrelated PRs. Unfortunately it may cause merge conflicts will several in-progress open PRs but the merge conflicts should be easy to resolve

[rootulp]

ADRs contain code blocks which are helpful at the time of reviewing the ADR but the code blocks have become stale so renaming portions of it to resolve this issue seems futile. We can either:

1. remove all the code blocks that have diverged from their real implementations in main
2. update all the code blocks

[evan-forbes]

could we also just leave them the way they are? They might not be that useful for outside contributor or as live documentation, but they are still useful for us to remember the thinking around past decisions.

[rootulp]

Sure, will leave ADRs as-is for now.

[rootulp]

Spun out two new issues so closing this