Hint when author concats different types into a string

**Describe the problem/challenge you have**

```
Message: unable to stamp object for resource [source-scanner] in supply chain [source-test-scan-to-url]: unable to apply ytt template: ytt: Error:
- unknown binary op: string + int
in
stdin.yml:6 | name: #@ data.values.workload.metadata.name + "-" + i
```

**Describe the solution you'd like**
```diff
Message: unable to stamp object for resource [source-scanner] in supply chain [source-test-scan-to-url]: unable to apply ytt template: ytt: Error:
- unknown binary op: string + int
in
stdin.yml:6 | name: #@ data.values.workload.metadata.name + "-" + i
+ (hint: to concatenate non-string values in a string, use str() or string.format())
```

**Anything else you would like to add:**

Source: https://kubernetes.slack.com/archives/CH8KCCKA5
A continuation of: #509

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Reproduce the string-plus-integer failure shown at stdin.yml:6 and trace where ytt formats the “unknown binary op” error. Done means this case includes the requested str() or string.format() hint while preserving the existing error location and message context.

Written by the indexing model from the issue text.