Added lots of customizations

[jesusrp98]

I've added a couple new parameters to SearchWidget, as well as NoItemFound:

• Now you can customize & reuse the NoItemFound widget. You can change its title & icon.
• Ability to select custom padding & contentPadding for the text box.
• Ability to change both enabled & focused borders.
• Customize prefix & suffix icons in the text box.
• Custom text style.
• Show custom widget when unsuccessful search.
• Updated example project to reflect these changes.
• Done quite a bunch of refactor.
• Updated .gitignore file.

If there's anything wrong, please contact me. You can update or change whatever you want :)

[apgapg]

Great you just did those which were scheduled on my next release. Big thanks for your contribution. Will review soon