Improve code quality in register and mylogin forms

[att78]

As Riku explains in his comment below, there is some repetitive code in formulas.

"I saw a lot of repetitiveness like touched.email && errors.email in every form field. I experienced little bit and found out how to make function that return true or false for given field (email, username etc).

type fieldKeys = keyof typeof values
const checkIfTouchedAndErrors = (fieldName: fieldKeys): boolean =>
!!(touched[fieldName] && errors[fieldName])

If you wan't to make this change it can be used like this checkIfTouchedAndErrors('email')"