Add support for moving Unity package files to canonical install locations in VersionHandler

[stewartmiles]

Some plugins want to move files about in Unity packages and Unity seems to require moving components into folders to upload to the asset store (see https://github.com/googlesamples/unity-jar-resolver/issues/190 )

Since importing multiple plugins with the same transitive dependencies at different versions when each version is imported at a different path is problematic (see https://github.com/googlesamples/unity-jar-resolver#unity-plugin-version-management ), then perhaps adding the option to have the Version Handler detect plugin files at unintended install locations and move them to the intended locations when it runs would workaround this issue.

For example, if a plugin contains the file:

• myplugin/myplugin.dll

and it's included in another plugin at:

• someotherplugin/myplugin/myplugin.dll

when the Version Handler runs it could detect the moved file and move it into the install location i.e myplugin/myplugin.dll instead.

The install location of a file could be stored in either the version handler manifest file (see https://github.com/googlesamples/unity-jar-resolver#version-handler-usage ) or applied as a label to each file.