[FEATURE] Allow user entering numbers in "Days before reminder" instead of list

[EmmaTellblom]

Is your feature request related to a problem? Please describe.
User has reported that they want to use "Days before reminders" for other functionality which is not possible when having a list that only allows 1-12 as values. Having it as a number field will enable for more customization.

Describe the solution you'd like
Change input field from list to number field.

Describe alternatives you've considered
None.

Additional context
Request from user ZhanZiyuan who wishes to use this feature for reminder of medication linked to menopause.

[ZhanZiyuan]

@EmmaTellblom Sorry, maybe my English statement is misleading. What I meant in #272 is that my request is not your highest priority and you can focus on what you're already doing currently. I'm sorry for annoying you. 🙏