v8.0 module release (#22975)

https://mattermost.atlassian.net/browse/MM-52079

```release-note
We upgrade the module version to 8.0. The new module path is github.com/mattermost-server/server/v8.
```


Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

server/plugin/health_check_test.go

@@ -0,0 +1,147 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package plugin
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/mattermost/mattermost-server/server/v8/channels/utils"
+	"github.com/mattermost/mattermost-server/server/v8/model"
+	"github.com/mattermost/mattermost-server/server/v8/platform/shared/mlog"
+)
+
+func TestPluginHealthCheck(t *testing.T) {
+	for name, f := range map[string]func(*testing.T){
+		"PluginHealthCheck_Success": testPluginHealthCheckSuccess,
+		"PluginHealthCheck_Panic":   testPluginHealthCheckPanic,
+	} {
+		t.Run(name, f)
+	}
+}
+
+func testPluginHealthCheckSuccess(t *testing.T) {
+	dir, err := os.MkdirTemp("", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	backend := filepath.Join(dir, "backend.exe")
+	utils.CompileGo(t, `
+		package main
+
+		import (
+			"github.com/mattermost/mattermost-server/server/v8/plugin"
+		)
+
+		type MyPlugin struct {
+			plugin.MattermostPlugin
+		}
+
+		func main() {
+			plugin.ClientMain(&MyPlugin{})
+		}
+	`, backend)
+
+	err = os.WriteFile(filepath.Join(dir, "plugin.json"), []byte(`{"id": "foo", "server": {"executable": "backend.exe"}}`), 0600)
+	require.NoError(t, err)
+
+	bundle := model.BundleInfoForPath(dir)
+	log := mlog.CreateConsoleTestLogger(true, mlog.LvlError)
+	defer log.Shutdown()
+
+	supervisor, err := newSupervisor(bundle, nil, nil, log, nil)
+	require.NoError(t, err)
+	require.NotNil(t, supervisor)
+	defer supervisor.Shutdown()
+
+	err = supervisor.PerformHealthCheck()
+	require.NoError(t, err)
+}
+
+func testPluginHealthCheckPanic(t *testing.T) {
+	dir, err := os.MkdirTemp("", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	backend := filepath.Join(dir, "backend.exe")
+	utils.CompileGo(t, `
+		package main
+
+		import (
+			"github.com/mattermost/mattermost-server/server/v8/model"
+			"github.com/mattermost/mattermost-server/server/v8/plugin"
+		)
+
+		type MyPlugin struct {
+			plugin.MattermostPlugin
+		}
+
+		func (p *MyPlugin) MessageWillBePosted(c *plugin.Context, post *model.Post) (*model.Post, string) {
+			panic("Uncaught error")
+		}
+
+		func main() {
+			plugin.ClientMain(&MyPlugin{})
+		}
+	`, backend)
+
+	err = os.WriteFile(filepath.Join(dir, "plugin.json"), []byte(`{"id": "foo", "server": {"executable": "backend.exe"}}`), 0600)
+	require.NoError(t, err)
+
+	bundle := model.BundleInfoForPath(dir)
+	log := mlog.CreateConsoleTestLogger(true, mlog.LvlError)
+	defer log.Shutdown()
+
+	supervisor, err := newSupervisor(bundle, nil, nil, log, nil)
+	require.NoError(t, err)
+	require.NotNil(t, supervisor)
+	defer supervisor.Shutdown()
+
+	err = supervisor.PerformHealthCheck()
+	require.NoError(t, err)
+
+	supervisor.hooks.MessageWillBePosted(&Context{}, &model.Post{})
+
+	err = supervisor.PerformHealthCheck()
+	require.Error(t, err)
+}
+
+func TestShouldDeactivatePlugin(t *testing.T) {
+	// No failures, don't restart
+	ftime := []time.Time{}
+	result := shouldDeactivatePlugin(ftime)
+	require.Equal(t, false, result)
+
+	now := time.Now()
+
+	// Failures are recent enough to restart
+	ftime = []time.Time{}
+	ftime = append(ftime, now.Add(-HealthCheckDeactivationWindow/10*2))
+	ftime = append(ftime, now.Add(-HealthCheckDeactivationWindow/10))
+	ftime = append(ftime, now)
+
+	result = shouldDeactivatePlugin(ftime)
+	require.Equal(t, true, result)
+
+	// Failures are too spaced out to warrant a restart
+	ftime = []time.Time{}
+	ftime = append(ftime, now.Add(-HealthCheckDeactivationWindow*2))
+	ftime = append(ftime, now.Add(-HealthCheckDeactivationWindow*1))
+	ftime = append(ftime, now)
+
+	result = shouldDeactivatePlugin(ftime)
+	require.Equal(t, false, result)
+
+	// Not enough failures are present to warrant a restart
+	ftime = []time.Time{}
+	ftime = append(ftime, now.Add(-HealthCheckDeactivationWindow/10))
+	ftime = append(ftime, now)
+
+	result = shouldDeactivatePlugin(ftime)
+	require.Equal(t, false, result)
+}