Typescript migration frontend

[MateuszKikmunter]

I migrated frontend app to TypeScript as it was the last part of the project not using it. I also updated and removed some outdated dependencies which made migration hard, e.g. react-form and react-toast-notifications. Instead I implemented form validation myself and replaced toast notifications with a newer package react-hot-toast.

[MateuszKikmunter]

@gitfrosh , please check this one before I'll merge it.

[gitfrosh]

Hey @MateuszKikmunter, thanks for working on this! Added some minor improvements and will merge asap.

[MateuszKikmunter]

Hey @MateuszKikmunter, thanks for working on this! Added some minor improvements and will merge asap.

No problem, thanks for looking at this PR. 😊