[chore] transport improvements

[NyaaaWhatsUpDoc]

Changes:

• improved transport error readability
• mark "bad hosts" as fastFail instead of failing immediately (allows picking up immediately if host comes back online)
• pull in latest go-byteutil version
• use rewindable body-reader for POST requests (otherwise body may be exhausted after first attempt)

Checklist:

• I/we have read the GoToSocial contribution guidelines.
• I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
• I/we have performed a self-review of added code.
• I/we have written code that is legible and maintainable by others.
• I/we have commented the added code, particularly in hard-to-understand areas.
• I/we have made any necessary changes to documentation.
• I/we have added tests that cover new code.
• I/we have run tests and they pass locally with the changes.
• I/we have run go fmt ./... and golangci-lint run.

[tsmethurst]

Nice one kimbe, thank you <3