Add IoT SDK Metrics V2 with feature encoding and metadata support

[rakshil14-2]

Issue #, if available:

Description of changes:

• Added metadata entries support to IoTDeviceSDKMetrics for passing key-value metrics through JNI to aws-c-mqtt
• Added IoTMetricEncoder that encodes CRT-level features (protocol, socket, TLS, proxy, jitter, session, queue, topic alias) into compact "ID/Value" format
• Added metrics creation/merge logic : auto-sets CRTVersion, validates IoTSDKMetricsVersion before merging SDK features
• Added user-configurable metrics API (withMetrics() / setMetrics()) for IoT SDK layer
• Renamed metricsEnabled → disableMetrics (opt-out pattern, default false)
• Stored TLS cipher preference and min TLS version on TlsContext for feature reporting
• Updated JNI layer to parse metadata entries list and pass to C
• Added unit tests for encoding, merging, and version validation

Breaking changes:

• withMetricsEnabled(boolean) → withDisableMetrics(boolean)
• getMetricsEnabled() → getDisableMetrics()

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.