Display DatePicker calendar popover when the date segments gain focus

### Provide a general summary of the feature here

When using the RAC `DatePicker`, it would be handy to display the calendar as soon as the input segments gain focus. Something akin to the `menuTrigger="focus"` option on the [ComboBox component](https://react-spectrum.adobe.com/react-aria/ComboBox.html#menu-trigger-behavior).

Thank you, and please let me know if you'd like any more information.

### 🤔 Expected Behavior?

Taking inspiration from the ComboBox, how about a `calendarTrigger` prop with the following values:

- `manual` (default): Calendar only opens when the user presses the trigger button or uses the arrow keys.
- `focus`: Calendar opens when the user focuses the DateInput input.

### 😯 Current Behavior

The `DatePicker` calendar can only be opened by using the `Button`.

### 💁 Possible Solution

_No response_

### 🔦 Context

Our UX team have found that people sometimes miss the button (no matter how prominent) to open the calendar. They have taken inspiration from IBM's Carbon which opens on focus:

https://carbondesignsystem.com/components/date-picker/usage/

### 💻 Examples

_No response_

### 🧢 Your Company/Team

RS/Website

### 🕷 Tracking Issue

_No response_