Add ij.run_script signature that takes file paths

Instead of taking the [full script text and language](https://github.com/imagej/pyimagej/blob/cf3bd1bf8814db5f436af517f0b99a48e6005c89/src/imagej/__init__.py#L321), we could just accept a fully qualified path, discern the language from the extension, and do

```python
with open(script_path, "r") as f:
script = "".join(f.readlines())
```

to avoid this boilerplate that is kind of annoying and feels unnecessary