Add @searchFieldPosition argument

[alex-ju]

Summary

Follow-up on #1752, gradually introducing @searchFieldPosition (after-options | trigger).

Description

<PowerSelect /> instances will have @searchFieldPosition set to before-options by default.
<PowerSelectMultiple /> instances will have @searchFieldPosition set to trigger by default with the option to change it to before-options.

<PowerSelectMultiple @searchEnabled={{true}} @searchFieldPosition="before-options" /> instances will have a search input placed in the dropdown, before the options, acting exactly as it currently does in <PowerSelect @searchEnabled={{true}} />.

[mkszepp]

@alex-ju thank you... i will look to find time in next days to review it

[mkszepp]

@alex-ju i have tested passing @searchFieldPosition for multiple and single select.
Multiple works great, but the @searchFieldPosition="trigger" on single doesn't work atm.

Do you have time to add also that option for single select?

[alex-ju]

@alex-ju i have tested passing @searchFieldPosition for multiple and single select. Multiple works great, but the @searchFieldPosition="trigger" on single doesn't work atm.

Do you have time to add also that option for single select?

I had a start on the single select as well, but it requires a bit more attention (esp on the a11y and focus management) so I was hoping to address it in a follow-up PR.

[mkszepp]

I had a start on the single select as well, but it requires a bit more attention (esp on the a11y and focus management) so I was hoping to address it in a follow-up PR.

ah, understood...
i would like to add in same PR, because we need to add the new paramenter in docs, so maybe other peoples are reporting us that the new paramenter is not working.

[alex-ju]

I had a start on the single select as well, but it requires a bit more attention (esp on the a11y and focus management) so I was hoping to address it in a follow-up PR.

ah, understood... i would like to add in same PR, because we need to add the new paramenter in docs, so maybe other peoples are reporting us that the new paramenter is not working.

makes sense, will try to carry on with this PR then when time allows

[alex-ju]

@mkszepp an accessible implementation of @searchFieldPosition="trigger" on single selection turns out to be rather complex. would you consider gradually introducing all combinations, by first getting @searchFieldPosition="after-options" for multiple selection?