Allow to change Gregorian date to the solar date when calendar is changed to Persian

[Chetna1510]

*Is your feature request related to a problem? Please describe.** In my shop when customer go to checkout page (I set the calendar showing in the billing section) I wanna customer can choose one day based on the Solar date (in calendar) for receiving products because in Iran few people used the Gregorian date and don't work on it.

Describe the solution you'd like I see that when I want to change the language calendar from (English-UK) to (Persian), only change the name on month and don't calculate the Gregorian date to the solar date.

The Solar date is based on the Solar Hijri calendar, which is the official calendar in Iran and follows a different system than the Gregorian calendar. Here's an example of a Solar date:

Solar date: 15 Khordad 1402

In this example:

"15" represents the day of the month. "Khordad" is the name of the month in the Solar Hijri calendar. Each month in this calendar has its own name. "1402" indicates the year in the Solar Hijri calendar. The Solar Hijri calendar is a solar calendar, which means it is based on the Earth's movement around the sun.

Additional context https://tychesoftwares.freshdesk.com/a/tickets/54312

[Chetna1510]

One more client has asked for this - https://tychesoftwares.freshdesk.com/a/tickets/59303