Bug 33480: Improve vendor aliases display in dropdown list

Bug 33480: Improve vendor aliases display in dropdown list

On bug 33103 we are adding the ability to filter vendors by aliases.
To make it possible in the ERM module we are adding the alias list in
the dropdown list. However it's not nicely displayed, especially if
there are several entries.

This patch suggests to display the aliases in a different line, and not
for the selected option.

To acchieve that we create a new Vue component FormSelectVendors.

Test plan:
Create several vendors, and add some aliases to them (keep one vendor
without alias)
Go to the ERM module go to the following page, search for vendors by
aliases, save the form, and confirm that everything is nice and works
correctly:
* Add/edit an agreement
* Add/edit a license
* Add/edit a local package
* Add a new package to a title (edit a title)

Signed-off-by: Pedro Amorim <pedro.amorim@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>