Setting project for LanguageServiceClient / LanguageServiceSettings is not possible

**Is your feature request related to a problem? Please describe.**
Using the `LanguageServiceClient` I would like to access another project then where my service account is located.

**Describe the solution you'd like**

* The `LanguageServiceClient` should respect `GOOGLE_CLOUD_PROJECT` environment variable
* The `LanguageServiceSettings` should have a `setProjectId()` similar to the `StorageOptions` etc.

**Describe alternatives you've considered**

Recreating the service account in the project seams to be the only workaround as per now.

**Additional context**

N/A