Plugin groups (#30320)

* add new pluginapi methods

* SAML login hook

* set ReAddRemovedMembers to true for plugin groups

* change to DoLogin signature for SAML

server/public/go.mod

@@ -17,6 +17,7 @@ require (
 	github.com/hashicorp/go-plugin v1.6.3
 	github.com/lib/pq v1.10.9
 	github.com/mattermost/go-i18n v1.11.1-0.20211013152124-5c415071e404
+	github.com/mattermost/gosaml2 v0.8.0
 	github.com/mattermost/ldap v0.0.0-20231116144001-0f480c025956
 	github.com/mattermost/logr/v2 v2.0.21
 	github.com/nicksnyder/go-i18n/v2 v2.5.0
@@ -37,6 +38,7 @@ require (
 
 require (
 	filippo.io/edwards25519 v1.1.0 // indirect
+	github.com/beevik/etree v1.1.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/fatih/color v1.18.0 // indirect
 	github.com/go-asn1-ber/asn1-ber v1.5.7 // indirect
@@ -44,7 +46,9 @@ require (
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/hashicorp/yamux v0.1.2 // indirect
+	github.com/jonboulle/clockwork v0.2.2 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
+	github.com/mattermost/xml-roundtrip-validator v0.1.0 // indirect
 	github.com/mattn/go-colorable v0.1.14 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/oklog/run v1.1.0 // indirect
@@ -52,6 +56,7 @@ require (
 	github.com/philhofer/fwd v1.1.3-0.20240916144458-20a13a1f6b7c // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/rogpeppe/go-internal v1.10.0 // indirect
+	github.com/russellhaering/goxmldsig v1.2.0 // indirect
 	github.com/segmentio/backo-go v1.1.0 // indirect
 	github.com/stretchr/objx v0.5.2 // indirect
 	github.com/tidwall/gjson v1.18.0 // indirect
@@ -67,7 +72,6 @@ require (
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20250124145028-65684f501c47 // indirect
 	google.golang.org/grpc v1.70.0 // indirect
 	google.golang.org/protobuf v1.36.4 // indirect
-	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
 	gopkg.in/natefinch/lumberjack.v2 v2.2.1 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 )