chore: deprecated warning message for Autocomplete

[siduck]

Closes: #434

https://github.com/frappe/frappe-ui/wiki/Guide-to-Migrate-Autocomplete-component-to-Combobox-&-MultiSelect

[surajshetty3416]

@siduck, you should ideally replace usages of Autocomplete example inside frappe-ui with Combobox. Otherwise, people using frappe-ui will keep getting these warnings, and they can’t do anything about it since it’s internal.

[netchampfaris]

@siduck

https://github.com/frappe/frappe-ui/wiki/Guide-to-Migrate-Autocomplete-component-to-Combobox-&-MultiSelect

This guide is incomplete without mentioning what the breaking changes were. for e.g., Autocomplete used to set the { label, value } object as the value but Combobox sets the primitive "value" as the value. so devs will have to make more than just template changes. they will have to update script section as well. you should add full examples for Combobox and MultiSelect migrating from Autocomplete.