feat(job-exec): add client variable support

[fbtravi]

What Add support for specifying an arbitrary API client identifier and version for google_cloud_run_v2_job resources.

Changes

Added client and client_version arguments to the google_cloud_run_v2_job resource in main.tf.

Introduced a new client variable (object) with optional name and version fields in variables.tf.

Updated default value for client to an empty object.

Why This allows providing metadata for API client identification when creating or managing Cloud Run jobs, improving traceability and integration consistency.

[fbtravi]

Hey @bharathkkb ! On macOS I hit an error running the Docker command (Go runtime crash with generate_docs), probably related to the processor architecture (Apple Silicon vs amd64 emulation). So I generated the docs locally and merged the client variable manually into the file. Is that enough?

[fbtravi]

@bharathkkb! Hello, is this good to proceed? Sorry for the inconvenience.