fix: fix panics, enable the forcetypeassert lint (#1123)

An unchecked type assertion panics on input it did not expect, as a missing `tool_cache` key did in https://gitea.com/gitea/runner/pulls/1122.

Every flagged site is now handled where it can fail, or typed so it cannot: a `lock.Keyed` replaces the two `sync.Map` mutex registries, and the reporter's outputs carry an explicit sent flag. Mocks keep their assertions, a mismatch there is a setup error the panic names.

Bugs it turned up (only the first is reachable from workflows):

1. A scalar `matrix.include` or `matrix.exclude`, e.g. `include: foo` or `include: [1, 2]`, panicked the runner with `interface conversion: interface {} is string, not map[string]interface {}`. Verified against `main`, it is now a workflow error. `OnSchedule` panicked the same way on a malformed `on.schedule` entry.
1. `ExternalURL()` panicked on the nil listener after `Close()`, the port is now resolved once at startup.
1. `errors.Is(err, git.ErrShortRef)` followed by `err.(*git.Error)` panics as soon as anything wraps that error, so it is `errors.As` now.
1. An output name the server acknowledged without ever being sent one was recorded as sent forever, which silently dropped a later value for that name.

48576ab3e5 fixes one discovered issue: a matrix key holding a nested object was logged and then run as if the job had no matrix, so it now fails like an unknown `exclude` key.
Reviewed-on: https://gitea.com/gitea/runner/pulls/1123
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>

act/common/outbound_ip.go

@@ -19,7 +19,9 @@ func GetOutboundIP() net.IP {
 	conn, err := net.Dial("udp", "8.8.8.8:80")
 	if err == nil {
 		defer conn.Close()
-		return conn.LocalAddr().(*net.UDPAddr).IP
+		if addr, ok := conn.LocalAddr().(*net.UDPAddr); ok {
+			return addr.IP
+		}
 	}
 
 	// So the machine cannot access the internet. Pick an IP address from network interfaces.