feat: add custom org ID to AddOrganizationRequest (#9720)

# Which Problems Are Solved

- It is not possible to specify a custom organization ID when creating
an organization. According to
https://github.com/zitadel/zitadel/discussions/9202#discussioncomment-11929464
this is "an inconsistency in the V2 API".

# How the Problems Are Solved

- Adds the `org_id` as an optional parameter to the
`AddOrganizationRequest` in the `v2beta` API.

# Additional Changes

None. 

# Additional Context

- Discussion
[#9202](https://github.com/zitadel/zitadel/discussions/9202)
- I was mostly interested in how much work it'd be to add this field.
Then after completing this, I thought I'd submit this PR. I won't be
angry if you just close this PR with the reasoning "we didn't ask for
it". 😄
- Even though I don't think this is a breaking change, I didn't add this
to the `v2` API yet (don't know what the process for this is TBH). The
changes should be analogous, so if you want me to, just request it.

---------

Co-authored-by: Stefan Benz <46600784+stebenz@users.noreply.github.com>

proto/zitadel/org/v2/org_service.proto

@@ -197,6 +197,14 @@ message AddOrganizationRequest{
     }
   ];
   repeated Admin admins = 2;
+  // optionally set your own id unique for the organization.
+  optional string org_id = 3 [
+    (validate.rules).string = {min_len: 1, max_len: 200},
+    (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_field) = {
+      max_length: 200;
+      example: "\"d654e6ba-70a3-48ef-a95d-37c8d8a7901a\"";
+    }
+  ];
 }
 
 message AddOrganizationResponse{

proto/zitadel/org/v2beta/org_service.proto

@@ -160,6 +160,14 @@ message AddOrganizationRequest{
     }
   ];
   repeated Admin admins = 2;
+  // optionally set your own id unique for the organization.
+  optional string org_id = 3 [
+    (validate.rules).string = {min_len: 1, max_len: 200},
+    (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_field) = {
+      max_length: 200;
+      example: "\"d654e6ba-70a3-48ef-a95d-37c8d8a7901a\"";
+    }
+  ];
 }
 
 message AddOrganizationResponse{