Plugin groups (#30320)

* add new pluginapi methods

* SAML login hook

* set ReAddRemovedMembers to true for plugin groups

* change to DoLogin signature for SAML

server/einterfaces/mocks/SamlInterface.go

@@ -8,6 +8,8 @@ import (
 	model "github.com/mattermost/mattermost/server/public/model"
 	request "github.com/mattermost/mattermost/server/public/shared/request"
 	mock "github.com/stretchr/testify/mock"
+
+	saml2 "github.com/mattermost/gosaml2"
 )
 
 // SamlInterface is an autogenerated mock type for the SamlInterface type
@@ -84,7 +86,7 @@ func (_m *SamlInterface) ConfigureSP(c request.CTX) error {
 }
 
 // DoLogin provides a mock function with given fields: c, encodedXML, relayState
-func (_m *SamlInterface) DoLogin(c request.CTX, encodedXML string, relayState map[string]string) (*model.User, *model.AppError) {
+func (_m *SamlInterface) DoLogin(c request.CTX, encodedXML string, relayState map[string]string) (*model.User, *saml2.AssertionInfo, *model.AppError) {
 	ret := _m.Called(c, encodedXML, relayState)
 
 	if len(ret) == 0 {
@@ -92,8 +94,9 @@ func (_m *SamlInterface) DoLogin(c request.CTX, encodedXML string, relayState ma
 	}
 
 	var r0 *model.User
-	var r1 *model.AppError
-	if rf, ok := ret.Get(0).(func(request.CTX, string, map[string]string) (*model.User, *model.AppError)); ok {
+	var r1 *saml2.AssertionInfo
+	var r2 *model.AppError
+	if rf, ok := ret.Get(0).(func(request.CTX, string, map[string]string) (*model.User, *saml2.AssertionInfo, *model.AppError)); ok {
 		return rf(c, encodedXML, relayState)
 	}
 	if rf, ok := ret.Get(0).(func(request.CTX, string, map[string]string) *model.User); ok {
@@ -104,15 +107,23 @@ func (_m *SamlInterface) DoLogin(c request.CTX, encodedXML string, relayState ma
 		}
 	}
 
-	if rf, ok := ret.Get(1).(func(request.CTX, string, map[string]string) *model.AppError); ok {
+	if rf, ok := ret.Get(1).(func(request.CTX, string, map[string]string) *saml2.AssertionInfo); ok {
 		r1 = rf(c, encodedXML, relayState)
 	} else {
 		if ret.Get(1) != nil {
-			r1 = ret.Get(1).(*model.AppError)
+			r1 = ret.Get(1).(*saml2.AssertionInfo)
 		}
 	}
 
-	return r0, r1
+	if rf, ok := ret.Get(2).(func(request.CTX, string, map[string]string) *model.AppError); ok {
+		r2 = rf(c, encodedXML, relayState)
+	} else {
+		if ret.Get(2) != nil {
+			r2 = ret.Get(2).(*model.AppError)
+		}
+	}
+
+	return r0, r1, r2
 }
 
 // GetMetadata provides a mock function with given fields: c