feat(terraform): Implement terraform service discovery (#6720)

...rraform-module/__fixtures__/service-custom-discovery.json

...urce/terraform-module/__fixtures__/service-discovery.json

...asource/terraform-module/__snapshots__/index.spec.ts.snap

lib/datasource/terraform-module/index.spec.ts

lib/datasource/terraform-module/index.ts

...ce/terraform-provider/__fixtures__/service-discovery.json

...ource/terraform-provider/__snapshots__/index.spec.ts.snap

lib/datasource/terraform-provider/index.spec.ts

lib/datasource/terraform-provider/index.ts

lib/manager/terraform/__snapshots__/extract.spec.ts.snap

lib/manager/terraform/modules.ts