feat: add today btn

[meghanmae]

Description

• added a 'today' button on the date time picker.
• I can revert, but I also enabled the adjacent months to reduce the amount of whitespace

Questions:

• Do you want a test written for this? I made a small attempt, but ran into some issues. Can try again if a test would be valuable.
• Are these too close together?
  

Ensure that your pull request has followed all the steps below:

• Code compilation
• Created tests which fail without the change (if possible)
• All tests passing
• Extended the README / documentation, if necessary

[ascott18]

next isn't currently active

[meghanmae]

Checking if today's date is allowed... is just passing 'new Date()' here sufficient? Is there any worry about time zones?

[ascott18]

It would certainly be easier to not do this. Leave it up to the developer to just not enable the "Today" button if they know for their use case that selecting today will be out of bounds of their validation rules.

This validation is happening before the timezone transformations has been applied, so yes, there will be timezone issues here. The other usage of isDateAllowed in emitInput occurs after timezone transformations.

[ascott18]

This is an unusual class name. The entire component is not a today-btn. Only the button itself inside the component's menu would make sense to have a today-btn class.

Consider a more appropriate class name like c-datetime-picker__menu--has-today-btn on the menu's contentClass, which also adheres to the (mildly consistent) use of BEM selectors in this project.

[meghanmae]

Maybe this should just be axed and if you click 'today' when there is a min/max value and today doesn't fall within it we just clamp to be within the bounds?