docs(storage): add samples for generate signed urls

[joshuatants]

Fixes #3081
Fixes #3082

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.01%. Comparing base (b96b407) to head (abccd19).
⚠️ Report is 18 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4525      +/-   ##
==========================================
- Coverage   95.02%   95.01%   -0.02%     
==========================================
  Files         195      195              
  Lines        7456     7456              
==========================================
- Hits         7085     7084       -1     
- Misses        371      372       +1     

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[joshuatants]

Sorry Carlos some more newbie questions:

1. Is there a way to use Storage Testbench? In C++ this could be set with various environment variables like GOOGLE_CLOUD_CPP_STORAGE_TEST_JSON_ENDPOINT or programmatically using RestEndpointOption or EndpointOption. Searching through the Rust repo turns up

   google-cloud-rust/src/storage/src/storage/signed_url.rs

   Line 822 in b255800

   emulator_hostname: Option<String>,

   and

   google-cloud-rust/src/gax-internal/src/host.rs

   Line 87 in b255800

   #[test_case(Some("localhost:5678"), "test.googleapis.com"; "emulator")]

   but these don't appear to be options to use the Testbench.
2. When runnig the integration tests locally they fail with the message

Caused by:
    code: 'Client specified an invalid argument', message: "This operation does not support custom billing projects at this time."

(For context, the tests that currently fail are for the samples set_public_access_prevention_unspecified, change_file_storage_class, and create bucket for object ACL, retention.)

I suspect this is because I'm currently using the project I set up here. I'm creating a new project but am unsure of what Billing Account and Location to select (screenshot). Is there a sample project I can follow?

Thank you.

[coryan]

Sorry Carlos some more newbie questions:

1. Is there a way to use Storage Testbench?

Maybe. But I think the testbench is missing some headers that we depend on. But why? The motivations for the testbench are: (1) to avoid flakes because you are using production, (2) to create specific errors.

For (2) we decided to launch HTTP (or gRPC) servers from within Rust. It is easy to do, and you can control sequence of messages much better than with the testbench (including timeouts).

For (1) same thing, we try to run as few tests as possible against production. I guess the examples could be excluded, but wouldn't you want at least one run against production for the examples? And we only have one-ish test.

2. When runnig the integration tests locally they fail with the message

Caused by:
    code: 'Client specified an invalid argument', message: "This operation does not support custom billing projects at this time."

You are running into #4370 maybe it would be nice to automatically disable the tracing test if the billing project is not enabled, or disable the gRPC tests if it was.

[coryan]

Caused by:
code: 'Client specified an invalid argument', message: "This operation does not support custom billing projects at this time."

You are running into #4370 maybe it would be nice to automatically disable the tracing test if the billing project is not enabled, or disable the gRPC tests if it was.

Fixed in #4584