reactor-plugins are not reloaded on subsequent invocations

### Affected version

1.0.4

### Bug description

I think this is a bug, but could also be seen as a feature request.

## Description

When a project contains a maven-plugin, e.g. https://github.com/mthmulders/polly/pull/877, then subsequent invocations of mvnd will not reload the changed plugins.

For example, let's assume the Mojo is not thread safe.

* change the Mojo to `threadSafe = false`
* run `mvnd verify`
* see the "threadSafe Warning`

Then

* change the Mojo back to `threadSafe = true`
* run `mvnd verify` again
* see that the Mojo is still not treated as threadsafe as it does not get reloaded

## Proposed solution

* `mvnd` could just reload -SNAPSHOT versioned plugins of a reactor (or any plugin, really).

That is easy to implement and is probably working for >> 90% of the cases

## Feature vs Bug

I think it is a bug because on `mvn` invocation the plugin is always reloaded and `mvnd` violates the principle of least surprise (from a UX perspective)

Reproduce the reported reactor maven-plugin scenario by changing a Mojo between threadSafe = false and threadSafe = true, then invoke mvnd verify twice and compare the behavior with mvn. Done means subsequent mvnd invocations reload the changed reactor plugin and no longer retain the earlier thread-safety warning.

Written by the indexing model from the issue text.