Add read_channel_content permission (#24118)

* Add read_channel_content permission

* fix tests

* update system console default permissions per role

* add read_channel_content to e2e defaultRolesPermissions

* Migration to include custom roles

* change deprecated isNotExactRole for isNotRole

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/authorization_test.go

@@ -33,11 +33,13 @@ func TestCheckIfRolesGrantPermission(t *testing.T) {
 		{[]string{model.SystemAdminRoleId}, model.PermissionManageSystem.Id, true},
 		{[]string{model.SystemAdminRoleId}, "non-existent-permission", false},
 		{[]string{model.ChannelUserRoleId}, model.PermissionReadChannel.Id, true},
+		{[]string{model.ChannelUserRoleId}, model.PermissionReadChannelContent.Id, true},
 		{[]string{model.ChannelUserRoleId}, model.PermissionManageSystem.Id, false},
 		{[]string{model.SystemAdminRoleId, model.ChannelUserRoleId}, model.PermissionManageSystem.Id, true},
 		{[]string{model.ChannelUserRoleId, model.SystemAdminRoleId}, model.PermissionManageSystem.Id, true},
 		{[]string{model.TeamUserRoleId, model.TeamAdminRoleId}, model.PermissionManageSlashCommands.Id, true},
 		{[]string{model.TeamAdminRoleId, model.TeamUserRoleId}, model.PermissionManageSlashCommands.Id, true},
+		{[]string{model.ChannelGuestRoleId}, model.PermissionReadChannelContent.Id, true},
 	}
 
 	for _, testcase := range cases {