Adopt .contract.js naming for contract definition files

[turadg]

What is the Problem Being Solved?

It's sometimes hard to find a contract file. They can appear anywhere in the source tree and have no distinguishing features in their names.

The lack of a consistent name also makes more work for #4770

Description of the Design

(from thread)

• Adopt a convention of .subtype.js for flavors of JS files
• Rename contract files to .contract.js
• Ensure they each have exactly one named export, a start function

Security Considerations

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Test Plan

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[turadg]

I'm running into this again where it's hard to find a particular contract. @dckc you were opposed to the .contract.js convention. Are you willing for there to be a file name/path convention at all? If so, what would you prefer?

One alternative to the file subtype is to have at most one contract per directory and name it as the contract like packages/run-protocol/vaultFactory/contract.js. Related files would be grouped in the same directory.

[dckc]

I'm running into this again where it's hard to find a particular contract.

Which one? What sort of search are you doing that fails?

you were opposed to the .contract.js convention.

It's not the convention I oppose; it's renaming. Renaming breaks web links, git blame, etc.
I think it's only cost-effective when the benefit is very substantial.