Add coverage calculation and badge (#127)

## Which problem is this PR solving?
Enhancements for
[#6572](jaegertracing/jaeger#6572)

## Description of the changes
-    Use retry upload action from main branch
-    Delete lines for model.pb.go from coverage
-    add badge to readme

## How was this change tested?
- 

## 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: Shreyas Kirtane <[email protected]>
Signed-off-by: Yuri Shkuro <[email protected]>
Signed-off-by: Yuri Shkuro <[email protected]>
Co-authored-by: Yuri Shkuro <[email protected]>
Co-authored-by: Yuri Shkuro <[email protected]>

Author: skirtan1

.codecov.yml

@@ -0,0 +1,22 @@
+codecov:
+  notify:
+    require_ci_to_pass: yes
+  strict_yaml_branch: main  # only use the latest copy on the main branch
+
+ignore:
+  - "model/v1/model.pb.go"
+  - "proto-gen/*/*"
+
+coverage:
+  precision: 2
+  round: down
+  range: "85...100"
+  status:
+    project:
+      default:
+        enabled: yes
+        target: 85%
+    patch:
+      default:
+        enabled: yes
+        target: 90%

.gitignore

@@ -1,3 +1,4 @@
 .idea/
 gen-*/
 .proto-gen-polyglot/
+coverage.txt

Makefile

@@ -40,6 +40,7 @@ swagger-validate:
 clean:
 	rm -rf *gen-* || true
 	rm -rf .*gen-* || true
+	rm -rf coverage.txt
 
 .PHONY: thrift
 thrift:	thrift-image clean $(THRIFT_FILES)

README.md

@@ -1,4 +1,5 @@
 # jaeger-idl [![Build Status][ci-img]][ci]
+[![Coverage Status][cov-img]][cov]
 
 A set of shared Thrift and Protobuf data model definitions used by the Jaeger components.
 
@@ -35,3 +36,5 @@ See [CONTRIBUTING](./CONTRIBUTING.md).
 
 [ci-img]: https://github.com/jaegertracing/jaeger-idl/actions/workflows/ci-unit-tests.yml/badge.svg
 [ci]: https://github.com/jaegertracing/jaeger-idl/actions/workflows/ci-unit-tests.yml
+[cov-img]: https://codecov.io/gh/jaegertracing/jaeger-idl/branch/main/graph/badge.svg
+[cov]: https://codecov.io/gh/jaegertracing/jaeger-idl/branch/main/