Customizable settings.xml path for Java transformation

## Problem

Currently in the Amazon Q extension, if I want to upgrade a java project, I must use the default `settings.xml` (`~/.m2/settings.xml`). But in complex scenarios there will be multiple different `settings.xml` file, e.g. `settings-dev.xml` and `settings-prod.xml`, currently I can't choose from them, I have to rename files (e.g. rename `settings-dev.xml` to `settings.xml`) to switch settings file.

## Expected behavior

In `/transform`, there should be a new option to input a custom `settings.xml` path.

Start at the /transform command and trace where the default ~/.m2/settings.xml path is selected. Done means the command accepts a custom settings.xml path and uses it for the Java transformation, while retaining the default behavior when no path is provided.

Written by the indexing model from the issue text.