Allow multiple semconv in --only flag

[lmolkova]

Alternative approach to #156

Usage diff:

Java generates all semconv except resources into one file

docker run --rm \
  -v ${SCRIPT_DIR}/opentelemetry-specification/semantic_conventions:/source \
  -v ${SCRIPT_DIR}/templates:/templates \
  -v ${ROOT_DIR}/semconv/src/main/java/io/opentelemetry/semconv/trace/attributes/:/output \
  otel/semconvgen:$GENERATOR_VERSION \
-  --exclude resource/** \
+  --only span,event,attribute_group,scope \
  -f /source code \
 ...

Resources:

docker run --rm \
- -v ${SCRIPT_DIR}/opentelemetry-specification/semantic_conventions/resource/:/source \
+ -v ${SCRIPT_DIR}/opentelemetry-specification/semantic_conventions:/source \
  -v ${SCRIPT_DIR}/templates:/templates \
  -v ${ROOT_DIR}/semconv/src/main/java/io/opentelemetry/semconv/resource/attributes/:/output \
  semconvgen:$GENERATOR_VERSION \
+ --only resource \
  -f /source code \
....

[lmolkova]

@Oberon00 thanks for the review!

@arminru could you please take a look and merge if you're fine with this change?

[Oberon00]

@lmolkova I guess this one then replaces #156? Maybe add "Closes #156" to the PR description to auto-close it on merge & have it linked in the sidebar.

[lmolkova]

@open-telemetry/specs-approvers can someone please take a look and merge? it unblocks code generation for 1.19.0 release open-telemetry/opentelemetry-specification#3299