feat: dynamic SDK version retrieval

[mfiedorowicz]

This pull request refactors how the SDK version is determined and propagated throughout the codebase, replacing the previous hardcoded SDKVersion constant with a dynamic value retrieved at runtime. The SDK name and version are now cached in both gRPC and DryRun clients, ensuring consistency and easier maintainability. Additional tests were added to verify correct SDK version detection and caching behavior.

SDK Version Detection and Propagation:

• Introduced getSDKVersion() to dynamically determine the SDK version using Go build info, with a fallback to "dev" if unavailable. The function checks module dependencies for the SDK version. (diode/client.go, diode/client.goR182-R198)
• Removed the hardcoded SDKVersion constant and updated all references to use the new dynamic value. (diode/client.go, [1]; diode/dryrun.go, [2]

Client Initialization and Metadata:

• Updated GRPCClient and DryRunClient structs to include sdkName and sdkVersion fields, which are set during client initialization and used in metadata and requests. (diode/client.go, [1] [2]; diode/dryrun.go, [3] [4]
• Changed user agent string and request metadata to use the cached SDK name and version from the client structs. (diode/client.go, [1] [2]; diode/dryrun.go, [3]
• Removed the now-unnecessary userAgent() helper function. (diode/client.go, diode/client.goL566-L570)

Testing Enhancements:

• Added tests to verify SDK version detection in various build environments and to ensure that SDK name and version are cached and consistent across multiple client instances for both gRPC and DryRun clients. (diode/client_test.go, [1]; diode/dryrun_test.go, [2]

[github-actions]

Go test coverage

STATUS	ELAPSED	PACKAGE	COVER	PASS	FAIL	SKIP
🟢 PASS	0.49s	github.com/netboxlabs/diode-sdk-go/cmd/diode-replay-dryrun	0.0%	0	0	0
🟢 PASS	1.33s	github.com/netboxlabs/diode-sdk-go/diode	19.2%	256	0	0

Total coverage: 78.7%

[leoparente]

LGTM