Fix enhance param error when there are multiple params

[CodePrometheus]

summary

When I intercepted the following method, I found that the parameter passed to skywalking is an array, and only the first parameter can be obtained.
For example, can only get ctx, A, C and msg.

func (ch *Ch) Test(ctx context.Context, A, B string, C, D bool, msg Publishing) (*Dc, error) {}

// tools/go-agent/tools/enhancement.go:63
func EnhanceParameterNames(fields *dst.FieldList, fieldType FieldListType) []*ParameterInfo {
	if fields == nil {
		return nil
	}
	result := make([]*ParameterInfo, 0)
	for i, f := range fields.List {
		var defineName string
		switch fieldType {
		case FieldListTypeParam:
			defineName = fmt.Sprintf("skywalking_param_%d", i)
		case FieldListTypeResult:
			defineName = fmt.Sprintf("skywalking_result_%d", i)
		case FieldListTypeRecv:
			defineName = fmt.Sprintf("skywalking_recv_%d", i)
		}
		if len(f.Names) == 0 {
			f.Names = []*dst.Ident{{Name: defineName}}
			result = append(result, newParameterInfo(defineName, f.Type))
		} else {
			for _, n := range f.Names {
				if n.Name == "_" {
					*n = *dst.NewIdent(defineName)
					break
				}
			}

			for _, n := range f.Names {
				result = append(result, newParameterInfo(n.Name, f.Type))
                                 // If there are multiple parameters in f.Names, only the first element of the array will be processed here
				break
			}
		}
	}
	return result
}

[mrproliu]

Why you need to modify the go.mod? It seems no dependency update.

[CodePrometheus]

Maybe it was caused by my executing go mod tidy locally.

[mrproliu]

Then, please restore to the upstream version.

[mrproliu]

Could you help to add more test case on this?

[CodePrometheus]

done~

[mrproliu]

Please update this PR by comments, thanks.

[mrproliu]

Once the CI success, it's LGTM. Thanks.

[CodePrometheus]

Thank you for your time as well, Teacher Liu.