feat(otlp-grpc-exporter): add gRPC channelOptions as config parameter

[vitorvasc]

Which problem is this PR solving?

Currently, the GrpcExporterTransport only allows configuring compression and user-agent options. This change exposes the full ChannelOptions interface, enabling users to tune settings such as:

• Keepalive: grpc.keepalive_time_ms, grpc.keepalive_timeout_ms, grpc.keepalive_permit_without_calls
• Reconnection: grpc.initial_reconnect_backoff_ms, grpc.max_reconnect_backoff_ms
• Message size limits: grpc.max_send_message_length, grpc.max_receive_message_length
• Any other @grpc/grpc-js channel options

Fixes #6231

Short description of the changes

Add channelOptions?: ChannelOptions parameter to the OTLPGRPCExporterConfigNode interface, passing it through the configuration workflow to the gRPC client constructor.

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Unit tests to ensure channelOptions passes through the configuration pipeline to the gRPC client constructor, with no changes to existing behavior:

• otlp-grpc-configuration.test.ts - config merging (user > fallback > default)
• grpc-exporter-transport.test.ts - transport accepts channelOptions
• convert-legacy-otlp-grpc-options.test.ts - legacy conversion passthrough

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.55%. Comparing base (0fd543c) to head (363e55a).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6332      +/-   ##
==========================================
- Coverage   95.58%   95.55%   -0.04%     
==========================================
  Files         314      315       +1     
  Lines        9590     9607      +17     
  Branches     2221     2228       +7     
==========================================
+ Hits         9167     9180      +13     
- Misses        423      427       +4     

Files with missing lines	Coverage Δ
.../configuration/convert-legacy-otlp-grpc-options.ts	71.42% <ø> (ø)
...-base/src/configuration/otlp-grpc-configuration.ts	100.00% <100.00%> (ø)
...-grpc-exporter-base/src/grpc-exporter-transport.ts	100.00% <ø> (ø)

... and 1 file with indirect coverage changes

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[vitorvasc]

With full ChannelOptions support, the compression and userAgent parameters could potentially be deprecated.

Here's how they could be passed instead:

import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-grpc';
import { compressionAlgorithms } from '@grpc/grpc-js';

const exporter = new OTLPTraceExporter({
    url: 'otel-collector.example.com:4317',
-	compression: 'gzip',
-	userAgent: 'my-service/1.0.0',
+    channelOptions: {
+        'grpc.primary_user_agent': 'my-service/1.0.0',
+        'grpc.default_compression_algorithm': compressionAlgorithms.gzip,
+        'grpc.keepalive_timeout_ms': 60000,
+        'grpc.keepalive_permit_without_calls': 1,
+        'grpc.initial_reconnect_backoff_ms': 5000,
+        'grpc.max_reconnect_backoff_ms': 5000,
+    },
});

Should we move forward and mark both those attributes as deprecated?

[Dhruv-Garg79]

@cjihrig @vitorvasc can we please get this merged?

[cjihrig]

@Dhruv-Garg79 this still requires review and approval from a project maintainer.