Change all references of transaction fee rate to a total fee

[yknl]

This PR changes all references of fee "rate" to a total fee. This brings it in line with what's actually implemented on core. The wire format specified in SIP005 needs to be updated as well. This change is needed because downstream integrations erroneously input a fee rate per byte instead of a total fee when building transactions, leading to the transaction being rejected for having a fee that's too low.

Related to: https://github.com/blockstack/stacks-transactions-js/issues/55 https://github.com/blockstack/stacks-transactions-js/issues/54

Type of Change

• [ ] New feature
• [x] Bug fix
• [x] API reference/documentation update
• [ ] Other

Does this introduce a breaking change?

Not a breaking change.

Are documentation updates required?

Yes

Testing information

Transactions built with the lib should continue to function when the fee is set correctly.

Checklist

• [x] Code is commented where needed
• [x] Unit test coverage for new or modified code paths
• [x] npm run test passes
• [x] Changelog is updated
• [x] Tag 1 of @yknl, @zone117x, @reedrosenbluth for review

[hstove]

Does this introduce a breaking change? Not a breaking change.

🤔

All good though, I like it.

Sidenote, I would like for this library to move to non-alpha, with proper SemVer. Preferably with semantic releases, but I can dream.