[Proto] Make protoFileInfo method public (#1998)

Summary:
In this commit, we make the protoFileInfo method public so that users
interested in parsing the proto files can use the method directly.

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**What type of PR is this?**

Other

**What package or component does this PR mostly affect?**


language/proto


**What does this PR do? Why is it needed?**

This PR makes a previously private method public so it can be reused to
parse proto files

**Which issues(s) does this PR fix?**

Fixes #

**Other notes for review**

language/proto/fileinfo.go

@@ -50,7 +50,7 @@ type Option struct {
 
 var protoRe = buildProtoRegexp()
 
-func protoFileInfo(dir, name string) FileInfo {
+func ProtoFileInfo(dir, name string) FileInfo {
 	info := FileInfo{
 		Path: filepath.Join(dir, name),
 		Name: name,

language/proto/fileinfo_test.go

@@ -233,7 +233,7 @@ import "second.proto";`,
 				t.Fatal(err)
 			}
 
-			got := protoFileInfo(dir, tc.name)
+			got := ProtoFileInfo(dir, tc.name)
 
 			// Clear fields we don't care about for testing.
 			got = FileInfo{

language/proto/generate.go

@@ -119,7 +119,7 @@ func RuleName(names ...string) string {
 func buildPackages(pc *ProtoConfig, dir, rel string, protoFiles, genFiles []string) []*Package {
 	packageMap := make(map[string]*Package)
 	for _, name := range protoFiles {
-		info := protoFileInfo(dir, name)
+		info := ProtoFileInfo(dir, name)
 		key := info.PackageName
 
 		if pc.Mode == FileMode {