Use a more proper error kind for quota conflicts, supporting the error type
*servicestate.QuotaChangeConflictError inside errToResponse and indicating what
sort of change the conflict is being used for.
Also update the unit tests for the daemon error response to check for this.
Signed-off-by: Ian Johnson <ian.johnson@canonical.com>
add final dots everywhere as recommended by go style guides and
preferred by @degville
adjust docs/error-kinds.go to that
clarify to use docs/error-kinds.go and that the direction of sync
is from code to forum for error kinds.
add what's missing and align forum and doc comments
then have a tool to generate what is on the forum:
$ cd docs
$ go run error-kinds.go
open question: when/if to have a dot at the end? always? only for
multi-sentence comments?
This is a simple reshuffle of the exiting error kinds in the
client into their own file with doc strings taken from:
https://forum.snapcraft.io/t/snapd-rest-api/17954
Some doc strings are missing but that is easy to see now via:
```
$ git grep "// ErrorKind.*: "
```
