Add a custom HostnameVerifier for OTLPHttpExporter

Is your feature request related to a problem? Please describe.
We want to ingest telemetry into an OTLP endpoint - the authentication mechanism for that endpoint is a SPIFFE implementation. SPIFFE uses mTLS and uses URIs in the X.509 certificate's SAN, not DNS names. Default hostnameVerification in the http clients requires a DNS name in SAN, which SPIFFE certificates do not have. I could not find a way to set a custom hostnameverifier for the OTLP exporter - due to this, hostnameVerification fails.

Describe the solution you'd like
A way to set custom hostnameVerification for http clients for the OTLP exporter - maybe something like setHostnameVerifier() here https://github.com/open-telemetry/opentelemetry-java/blob/main/exporters/sender/okhttp/src/main/java/io/opentelemetry/exporter/sender/okhttp/internal/OkHttpHttpSender.java#L106

Describe alternatives you've considered
We've explored running OTel collector sidecars for authentication, however that leads to increased resource usage and we would like to achieve this using the SDK if possible.

Additional context
Add any other context or screenshots about the feature request here.

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Start with exporters/sender/okhttp/src/main/java/io/opentelemetry/exporter/sender/okhttp/internal/OkHttpHttpSender.java at the referenced client setup point, then trace how OTLPHttpExporter configures its HTTP client. Done means callers can provide a custom HostnameVerifier so SPIFFE certificates using URI SANs can pass hostname verification.