Feature/new style names

[MaximVanhove]

This PR adds support for the new FA6 styles as mentioned in issue #7

Newly added styles:

<i class="fat fa-file"></i>
<i class="fa-thin fa-file"></i>
<i class="fa-brands fa-twitter"></i>
<i class="fa-duotone fa-file"></i>
<i class="fa-light fa-file"></i>
<i class="fa-regular fa-file"></i>
<i class="fa-solid fa-file"></i>
<i class="fa-sharp fa-light fa-file"></i>
<i class="fa-sharp fa-regular fa-file"></i>
<i class="fa-sharp fa-solid fa-file"></i>
<i class="fasl fa-file"></i>
<i class="fasr fa-file"></i>
<i class="fass fa-file"></i>

Note that this PR contains the same changes from PR #8 so that PR should be merged first.