Changes to acceptable values for bySetPos and byMonthDay to be consistent with iCalendar spec

[stevenpal]

About this Pull Request

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  • This change introduces two fixes to make the repeating rules for bySetPos and byMonthDay consistent with the iCalendar spec.
• What is the current behavior? (You can also link to an open issue here)
  • bySetPos currently only allows a single number to be passed in.
  • bySetPos currently only allows values between -1 and 4.
  • byMonthDay currently only allows values between 1 and 31.
  • If multiple days are specified for byDay when also specifying bySetPos, only the first day passed in the array is used and the remaining ones are discarded.
• What is the new behavior (if this is a feature change)?
  • bySetPos is now allowed to be passed in as both a number or an array.
  • bySetPos now allows values between -366 to -1 and 1 to 366.
  • byMonthDay now allows values between -31 to -1 and 1 to 31.
  • If multiple days are specified for byDay, they are all used in conjunction with bySetPos and none are discarded.
• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
  • If you're relying on additional values of byDay being discarded when being used with bySetPos, that would be a change to existing behavior. Otherwise, this adds functionality rather than removing or changing it.
• Other information:
  • The iCalendar spec describes the guidelines for bySetPos and byMonthDay: https://icalendar.org/iCalendar-RFC-5545/3-3-10-recurrence-rule.html
  • There are two tests failing off of the develop branch that are unrelated to these changes. They are related to support for Luxon and Day.js. I didn't try to fix those as I don't know much about those libraries.

Pull Request Checklist

• My code follows the code style of this project
  • Run npm run lint to double check
• My change requires a change to the documentation
  • I have updated the documentation accordingly
• I have added tests to cover my changes
  • Run npm run test to run the unit tests and npm run coverage to generate a coverage report
• All new and existing tests passed
• My commit messages follow the commit guidelines

[sebbo2002]

🎉 This PR is included in version 3.6.0-develop.1 🎉

The release is available on:

• npm package (@next dist-tag)
• GitHub release
• v3.6.0-develop.1

Your semantic-release bot 📦🚀

[sebbo2002]

🎉 This PR is included in version 3.6.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release
• v3.6.0

Your semantic-release bot 📦🚀