allow trigger slot customisation

Allows trigger button of TNavigationDropdown to be customisable using default slot.

This change is required for new filter ux's navigation dropdown switcher design from figma.

Usage example:

        <t-navigation-dropdown>
          <div class="text-xl text-[#1C1C21] flex items-center gap-2">
            <chart-box-outline-icon />
            {{ page.title }}
            <swap-horizontal-icon class="text-[#727184]" :size="16" />
          </div>
        </t-navigation-dropdown>

Icons Backend PR

Screenshot 2022-11-15 at 4 45 55 PM

topcoat-data / topcoat-public

allow trigger slot customisation #180