Selectively disable printing chosen warnings

There might be warnings that the user might not be intersted in. So it would be nice to reduce the noise by being able to selectively disable them.

This could probably be done by using the `-nowarning` flag and have an optional parameter. Something like

```
-nowarning=WRN:PA0123
```

Possibly also with shortened name

```
-nowarning=PA0123
```

Multiple warnings disabled just as a comma separated list:

```
-nowarning=PA0123,PA0124,PA0125
```

Start by locating the existing `-nowarning` command-line handling and the code that emits warning identifiers such as `PA0123`. Verify how a single warning is currently printed, then define completion as accepting one or more warning identifiers, including the shown comma-separated form, and suppressing only those warnings.

Written by the indexing model from the issue text.