Operation request: XSLT processor

### Summary

An operation to process XSLT over XML input.

https://en.wikipedia.org/wiki/XSLT

### Example

Input
```xml

John
Smith


Morka
Ismincius

```

XSLT
```xml

```

Output
```xml

John
Morka

```

No files, tests, or entry points are named. Start by locating existing operation implementations and the project’s dependency approach, then determine how the supplied XML and XSLT example should be represented and tested; done means the operation produces the shown XML output.

Written by the indexing model from the issue text.