* [feature] Provide .well-known/host-meta endpoint
This adds the host-meta endpoint as Mastodon clients use this to
discover the API domain to use when the host and account domains aren't
the same.
* Address review comments
* start pulling out + replacing urfave and config
* replace many many instances of config
* move more stuff => viper
* properly remove urfave
* move some flags to root command
* add testrig commands to root
* alias config file keys
* start adding cli parsing tests
* reorder viper init
* remove config path alias
* fmt
* change config file keys to non-nested
* we're more or less in business now
* tidy up the common func
* go fmt
* get tests passing again
* add note about the cliparsing tests
* reorganize
* update docs with changes
* structure cmd dir better
* rename + move some files around
* fix dangling comma
