WIP for #1289: Use OcSelect component for OcAutocomplete internally

[paulneubauer]

Basic implementation has been done, still some points have to be added to complete issue 1289.

• Styling should be refactored because the dom hierarchy changed due using oc-select
• During delayed fetch loading spinner should be added again
• There are also changes made in the Oc-Select, so the last sample example implementation should be updated (using filter)
• It should be checked if aria is still implemented the right way (vue-select uses it as far as I know but still should be checked)

Thats all. Thanks for the challenge I really liked it :)

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[dschmidt]

The issue is mentioned in the title but not actually linked: #1289

[kulmann]

Superseded by #1521