Allows creating new remote clusters without providing a password (#27864)

* Allows creating new remote clusters without providing a password

If the endpoint receives a request with no password, it will generate
one internally and return it in the response, so the frotend can show
it to the user.

* Use a random string instead of a UUID for the generated password

* Update function name to avoid CString reference and adds assertion

* Update server/channels/utils/textgeneration.go

Co-authored-by: Eva Sarafianou <eva.sarafianou@gmail.com>

* Extends the charset

---------

Co-authored-by: Eva Sarafianou <eva.sarafianou@gmail.com>

server/public/model/remote_cluster.go

@@ -155,6 +155,7 @@ type RemoteClusterWithPassword struct {
 type RemoteClusterWithInvite struct {
 	RemoteCluster *RemoteCluster `json:"remote_cluster"`
 	Invite        string         `json:"invite"`
+	Password      string         `json:"password,omitempty"`
 }
 
 func newIDFromBytes(b []byte) string {