plugins/wilder: migrate to mkNeovimPlugin

[GaetanLepage]

This was a tricky one.
This plugin has both a classic .setup(opts) configuration pattern and another imperative method to configure other options:

wilder.set_option('renderer', wilder.popupmenu_renderer({
  highlighter = {
    wilder.lua_pcre2_highlighter(),
    wilder.lua_fzy_highlighter(),
  },
  highlights = {
    accent = wilder.make_hl('WilderAccent', 'Pmenu', {{a = 1}, {a = 1}, {foreground = '#f4468f'}}),
  },
}))

In the end, I used the conventional free-form settings option and added an extra option called options (attrsOf anything) that will be mapped to wilder.set_option calls.

• plugins/wilder: remove rename warning (2yo)
• plugins/wilder: migrate to mkNeovimPlugin

Tracking: #2638