fix: bind:files for fileinput

[jjagielka]

Closes #473

📑 Description

Re-factoring of the Fileinput component:

• inheritance from Input component
• bind to files and value

✅ Checks

• My pull request adheres to the code style of this project
• My code requires changes to the documentation
• I have updated the documentation as required
• I have checked the page with https://validator.unl.edu/
• All the tests have passed
• My pull request is based on the latest commit (not the npm version).

ℹ Additional Information

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[shinokada]

Let me know when it's ready.

[jjagielka]

You can proceed now.