otDnsSetNameCompressionEnabled() function

Enables/disables the "DNS name compression" mode. By default DNS name compression is enabled. When disabled, DNS names are appended as full and never compressed. This is applicable to OpenThread's DNS and SRP client/server modules. This is intended for testing only and available when `OPENTHREAD_CONFIG_REFERENCE_DEVICE_ENABLE` config is enabled. Note that in the case `OPENTHREAD_CONFIG_MULTIPLE_INSTANCE_ENABLE` is used, this mode applies to all OpenThread instances (i.e., calling this function enables/disables the compression mode on all OpenThread instances).