[MaterialDatePicker] Choose different Calendar API and define custom DateTime Format

[IamMitsuo]

Is your feature request related to a problem? Please describe.
The current issue is that MaterialDatePicker is using java.util.Calendar (Java 7) as an underlying API to get UTC epoch millisecond and datetime format, and convert it to Month object where year property is retrieved from Calendar.get(Calendar.YEAR). This causes date string to always show year in Christian Era and/or B.C.E. As a Thai user, most of Thai are familiar with Buddhist Calendar (Buddhist year = Christian year + 543 e.g. 2021 = 2564), so elder users tend to not know which Christian year of their birthdate.

Describe the solution you'd like

• It would be great if we can customize or delegate how Month object is created, so it does not limit to only java.util.Calendar API, but open to java.time.chrono.ThaiBuddhistDate or org.threeten.bp.chrono.ThaiBuddhistDate (Threeten ABP).

MaterialDatePicker.Builder
    .datePicker()
    .setCustomMonth(CustomMonth())

open class CustomMonth(private val thaiBuddhistDate: ThaiBuddhistDate) : Month() {
     
     override fun getYear(): Int {
          return thaiBuddhistDate.getLong(ChronoField.YEAR).toInt()
     }
}

• Moreover, a custom date format should be a feature of MaterialDatePicker as well.

Additional context
Example screenshots from another library (ThaiDateTimePicker - very old library)