fix(dropdown): clearable icon was missing or misaligned

[lubber-de]

Description

clearable icon ...

• was missing when used inside a search selection dropdown
• was misaligned when used inside an inline dropdown

The basic fixes where already implemented but only if the clearable class was set manually, which this PR now automatically adds when the clearable setting is used.

Testcase

https://jsfiddle.net/lubber/nwjqr7Le/

Screenshot

Broken

Fixed