Migrate sampling.thrift (#132)

## Which problem is this PR solving?
- jaegertracing/jaeger#6617

## Description of the changes
- generate sampling.thrift code

## How was this change tested?
- ci

## Checklist
- [x] I have read
https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
- [x] I have signed all commits
- [ ] I have added unit tests for the new functionality
- [ ] I have run lint and test steps successfully
  - for `jaeger`: `make lint test`
  - for `jaeger-ui`: `npm run lint` and `npm run test`

Signed-off-by: nabil salah <nabil.salah203@gmail.com>

Makefile

@@ -51,6 +51,7 @@ thrift:
 	$(THRIFT) -o /data --gen go:$(THRIFT_GO_ARGS) -out /data/$(THRIFT_GEN_DIR) /data/thrift/jaeger.thrift
 	$(THRIFT) -o /data --gen go:$(THRIFT_GO_ARGS) -out /data/$(THRIFT_GEN_DIR) /data/thrift/zipkincore.thrift
 	$(THRIFT) -o /data --gen go:$(THRIFT_GO_ARGS) -out /data/$(THRIFT_GEN_DIR) /data/thrift/agent.thrift
+	$(THRIFT) -o /data --gen go:$(THRIFT_GO_ARGS) --out /data/$(THRIFT_GEN_DIR) /data/thrift/sampling.thrift
 	$(SED) -i.bak 's|"zipkincore"|"$(JAEGER_IMPORT_PATH)/thrift-gen/zipkincore"|g' $(THRIFT_GEN_DIR)/agent/*.go
 	$(SED) -i.bak 's|"jaeger"|"$(JAEGER_IMPORT_PATH)/thrift-gen/jaeger"|g' $(THRIFT_GEN_DIR)/agent/*.go
 	rm -rf thrift-gen/*/*-remote thrift-gen/*/*.bak