feat: allow switching document when using templates (#1571)

Adds the ability to upload a custom document when using a template.

This is useful when you have a given fixed template with placeholder
values that you want to decorate with Documenso fields but will then
create a final specialised document when sending it out to a given
recipient.

packages/trpc/server/template-router/schema.ts

@@ -47,6 +47,7 @@ export const ZCreateDocumentFromTemplateMutationSchema = z.object({
       return new Set(emails).size === emails.length;
     }, 'Recipients must have unique emails'),
   distributeDocument: z.boolean().optional(),
+  customDocumentDataId: z.string().optional(),
 });
 
 export const ZDuplicateTemplateMutationSchema = z.object({