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/exprparser/interpreter_test.go

@@ -11,6 +11,7 @@ import (
 	"gitea.com/gitea/runner/act/model"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestLiterals(t *testing.T) {
@@ -523,7 +524,9 @@ func TestOperatorsBooleanEvaluation(t *testing.T) {
 			assert.NoError(t, err) //nolint:testifylint // pre-existing issue from nektos/act
 
 			if expected, ok := tt.expected.(float64); ok && math.IsNaN(expected) {
-				assert.True(t, math.IsNaN(output.(float64)))
+				number, ok := output.(float64)
+				require.True(t, ok, "want a number, got %T", output)
+				assert.True(t, math.IsNaN(number))
 			} else {
 				assert.Equal(t, tt.expected, output)
 			}