Enable search icon & customise search placeholder, add "possible" in phoneObject#411

1. Could we enable the search icon and allow users to customise the search placeholder rather than being restricted to the initial country name? Here is the code for reference: ```vue <div v-if="dropdownOptions.showSearchBox" class="vti__search_box_container"> <slot name="search-icon"></slot> <input class="vti__input vti__search_box" aria-label="Search by country name or country code" :placeholder="dropdownOptions.searchBoxPlaceholder || (sortedCountries.length ? sortedCountries[0].name : '')" type="text" v-model="searchQuery" @click.stop /> </div> ``` 2. Add "possible" in phoneObject, so user could know if this number might be right