(core) move home server into core

Summary: This moves enough server material into core to run a home server.  The data engine is not yet incorporated (though in manual testing it works when ported).

Test Plan: existing tests pass

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2552

app/gen-server/lib/Permissions.ts

@@ -0,0 +1,21 @@
+export enum Permissions {
+  NONE          = 0x0,
+  // Note that the view permission bit provides view access ONLY to the resource to which
+  // the aclRule belongs - it does not allow listing that resource's children. A resource's
+  // children may only be listed if those children also have the view permission set.
+  VIEW          = 0x1,
+  UPDATE        = 0x2,
+  ADD           = 0x4,
+  // Note that the remove permission bit provides remove access to a resource AND all of
+  // its child resources/ACLs
+  REMOVE        = 0x8,
+  SCHEMA_EDIT   = 0x10,
+  ACL_EDIT      = 0x20,
+  EDITOR        = VIEW | UPDATE | ADD | REMOVE,   // tslint:disable-line:no-bitwise
+  ADMIN         = EDITOR | SCHEMA_EDIT,           // tslint:disable-line:no-bitwise
+  OWNER         = ADMIN | ACL_EDIT,               // tslint:disable-line:no-bitwise
+
+  // A virtual permission bit signifying that the general public has some access to
+  // the resource via ACLs involving the everyone@ user.
+  PUBLIC        = 0x80
+}