MM-10703 Adding blank request context to plugin hooks for future use. (#9043)

* Adding blank request context to plugin hooks for future use.

* Rename RequestContext to Context

* Adding context to ServeHTTP and ExecuteCommand

* Fixing import cycle in test.

web/context.go

@@ -14,6 +14,7 @@ import (
 	"github.com/mattermost/mattermost-server/app"
 	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
+	"github.com/mattermost/mattermost-server/plugin"
 	"github.com/mattermost/mattermost-server/utils"
 )
 
@@ -526,3 +527,11 @@ func (c *Context) RequireRoleName() *Context {
 
 	return c
 }
+
+func (c *Context) ToPluginContext() *plugin.Context {
+	return &plugin.Context{
+		//sessionId: c.Session.Id,
+		//requestId: c.RequestId,
+		//userIp: c.IpAddress,
+	}
+}