Merge branch 'v2' into v3

# Conflicts:
#	internal/sharedtest/custom_attributes.go
#	lduser/user_builder_benchmark_test.go
#	lduser/user_serialization_benchmark_test.go
#	lduser/user_serialization_easyjson_benchmark_test.go
#	ldvalue/value_base.go
#	ldvalue/value_json_easyjson_conversion.go
#	ldvalue/value_serialization.go
#	ldvalue/value_serialization_easyjson_test.go
#	ldvalue/value_serialization_test.go

Author: eli-darkly