[GH-16199] add IsValid to model OpenDialogRequest (#26526)

* [GH-16199] add IsValid to model OpenDialogRequest

* [GH-16199] add IsValid to model OpenDialogRequest, revert remove of translations

* [GH-16199] fix tests after revert

* [GH-16199] add IsValid to model OpenDialogRequest

* [GH-16199] revert validation of icon url

* [GH-16199] update go sum

* [GH-16199] log warning for invalid dialog

* [GH-16199] log error for invalid dialog

* [GH-16199] log warning for invalid dialog

* [GH-16199] fix golang-ci

---------

Co-authored-by: Lukas Eipert <git@leipert.io>
Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/go.mod

@@ -13,6 +13,7 @@ require (
 	github.com/gorilla/mux v1.8.1
 	github.com/gorilla/websocket v1.5.1
 	github.com/hashicorp/go-hclog v1.6.2
+	github.com/hashicorp/go-multierror v1.1.1
 	github.com/hashicorp/go-plugin v1.6.0
 	github.com/lib/pq v1.10.9
 	github.com/mattermost/go-i18n v1.11.1-0.20211013152124-5c415071e404
@@ -40,6 +41,7 @@ require (
 	github.com/go-asn1-ber/asn1-ber v1.5.5 // indirect
 	github.com/golang/protobuf v1.5.3 // indirect
 	github.com/google/uuid v1.6.0 // indirect
+	github.com/hashicorp/errwrap v1.0.0 // indirect
 	github.com/hashicorp/yamux v0.1.1 // indirect
 	github.com/kr/pretty v0.3.0 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect