Fixes all our Go file imports to match the preferred spec that we've _mostly_ been using. For example:
```
import (
"context"
"time"
"github.com/prometheus/client_golang/prometheus"
"golang.org/x/xerrors"
"gopkg.in/natefinch/lumberjack.v2"
"cdr.dev/slog/v3"
"github.com/coder/coder/v2/codersdk/agentsdk"
"github.com/coder/serpent"
)
```
3 groups: standard library, 3rd partly libs, Coder libs.
This PR makes the change across the codebase. The PR in the stack above modifies our formatting to maintain this state of affairs, and is a separate PR so it's possible to review that one in detail.
re: #13327
Adds local interfaces to `coder netcheck` and checks their MTUs for potential problems.
This is mostly relevant for end-user systems where VPNs are common. We _could_ also add it to coderd healthcheck, but until I see coderd connecting to workspaces over a VPN in the wild, I don't think its worth the UX effort.
Netcheck results get the following:
```
"interfaces": {
"error": null,
"severity": "ok",
"warnings": null,
"dismissed": false,
"interfaces": [
{
"name": "lo0",
"mtu": 16384,
"addresses": [
"127.0.0.1/8",
"::1/128",
"fe80::1/64"
]
},
{
"name": "en8",
"mtu": 1500,
"addresses": [
"192.168.50.217/24",
"fe80::c13:1a92:3fa5:dd7e/64"
]
}
]
}
```
_Technically_ not back compatible if anyone is parsing `coder netcheck` output as JSON, since the original output is now under `"derp"` in the output.
Adds checks to coderd/healthcheck/derphealth for STUN issues:
- Alerts if there is not least one healthy STUN server,
- Alerts if we see variable port mapping.
Relates to #8965
- Added error codes for separate code paths in health checks
- Prefixed errors and warnings with error code prefixes
- Added a docs page with details on each code, cause and solution
Co-authored-by: Muhammad Atif Ali <atif@coder.com>