Replacing panics with Result returns, and adds platform-specific status codes

[masa-koz]

Description

This pull request to src/lib.rs includes changes to improve error handling by replacing panics with Result returns, and adds platform-specific status codes to inspect Err's content.

Testing

cargo test

Documentation

No

[nibanks]

1. Does Rust allow for non-zero Ok status codes? For instance, we have the 'pending' status.
2. Should we return Ok(status) here?

[masa-koz]

Yes, Rust allows to return Ok(status), so we can inform whether the operation is complete or pending.
But I'm not sure that complete/pending information is useful.
AFAIK, msquic doesn't provide the function to wait when pending returns. So, I consider that we don't have to return complete/pending information.

[nibanks]

If this returns an Err will unwrap trigger the panic now?

[masa-koz]

Yes. If we want to avoid panic in test, we can write as below:

    let api = match Api::new() {
        Ok(api) => api,
        Err(status) => {
            println!("Failed to open MsQuic: 0x{:x}", status);
            return;
        }
    };

[masa-koz]

I've refactored error handling in tests in the latest commit.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.75%. Comparing base (9c41c71) to head (7709f54).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4690      +/-   ##
==========================================
- Coverage   86.81%   86.75%   -0.06%     
==========================================
  Files          56       56              
  Lines       17361    17361              
==========================================
- Hits        15072    15062      -10     
- Misses       2289     2299      +10     

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