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>

internal/integration/client.go

@@ -293,6 +293,15 @@ func SetOrgID(ctx context.Context, orgID string) context.Context {
 	return metadata.NewOutgoingContext(ctx, md)
 }
 
+func (i *Instance) CreateOrganizationWithCustomOrgID(ctx context.Context, name, orgID string) *org.AddOrganizationResponse {
+	resp, err := i.Client.OrgV2.AddOrganization(ctx, &org.AddOrganizationRequest{
+		Name:  name,
+		OrgId: gu.Ptr(orgID),
+	})
+	logging.OnError(err).Fatal("create org")
+	return resp
+}
+
 func (i *Instance) CreateOrganizationWithUserID(ctx context.Context, name, userID string) *org.AddOrganizationResponse {
 	resp, err := i.Client.OrgV2.AddOrganization(ctx, &org.AddOrganizationRequest{
 		Name: name,