feat(create-task): replace Autocomplete with AutoCompleteField for assignees

[Innagl]

Describe your changes

Migrated the assignees field in Modals/CreateTask/index.tsx from the raw MUI Autocomplete component to the shared "AutoCompleteField" wrapper.

Write your issue number after "Fixes "

Fixes #3759

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[MuhammadKhalilzadeh]

Thank you @Innagl
LGTM 👍🏻