Start writing role to database (#3120)

Scaffolding for guest members in channels

Release notes:
- You can now set channels to "public" which will allow anyone to join
and become a member. In a future release guests joining public channels
will have reduced permissions.

Cargo.lock

@@ -1625,6 +1625,7 @@ dependencies = [
  "theme",
  "util",
  "workspace",
+ "zed-actions",
 ]
 
 [[package]]
@@ -10174,6 +10175,7 @@ name = "zed-actions"
 version = "0.1.0"
 dependencies = [
  "gpui",
+ "serde",
 ]
 
 [[package]]