feat: implement global flag for org selection (#12276)

* feat: implement global flag for org selection

Any command can use '-z' to override org context

cli/testdata/coder_--help.golden

@@ -82,6 +82,10 @@ variables or flags.
       --no-version-warning bool, $CODER_NO_VERSION_WARNING
           Suppress warning when client and server versions do not match.
 
+  -z, --organization string, $CODER_ORGANIZATION
+          Select which organization (uuid or name) to use This overrides what is
+          present in the config file.
+
       --token string, $CODER_SESSION_TOKEN
           Specify an authentication token. For security reasons setting
           CODER_SESSION_TOKEN is preferred.