fix(datetime): enter closes keyboard when typing time (#28848)

Issue number: resolves #28325

---------

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## What is the current behavior?
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When typing the time into the date picker pressing "Enter" does not
close the on-screen keyboard.

## What is the new behavior?
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this PR. -->

- Pressing "Enter" closes the on-screen keyboard

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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screenshots of how the component looks before and after the change. -->


Test:

⚠️ While I have a test for this, please also test this on a physical
Android device.

1. Go to `src/components/datetime/test/basic`
2. Open the time picker (in any of the date times)
3. Tap the time to open the keyboard
4. Press "Enter" on Android. Observe that the keyboard closes.

Dev build: `7.6.6-dev.11705528328.1ef5e17b`

core/src/components/picker-internal/picker-internal.tsx

@@ -265,6 +265,7 @@ export class PickerInternal implements ComponentInterface {
 
       inputEl.focus();
     } else {
+      // TODO FW-5900 Use keydown instead
       el.addEventListener('keypress', this.onKeyPress);
       this.destroyKeypressListener = () => {
         el.removeEventListener('keypress', this.onKeyPress);
@@ -550,6 +551,21 @@ export class PickerInternal implements ComponentInterface {
           tabindex={-1}
           inputmode="numeric"
           type="number"
+          onKeyDown={(ev: KeyboardEvent) => {
+            /**
+             * The "Enter" key represents
+             * the user submitting their time
+             * selection, so we should blur the
+             * input (and therefore close the keyboard)
+             *
+             * Updating the picker's state to no longer
+             * be in input mode is handled in the onBlur
+             * callback below.
+             */
+            if (ev.key === 'Enter') {
+              this.inputEl?.blur();
+            }
+          }}
           ref={(el) => (this.inputEl = el)}
           onInput={() => this.onInputChange()}
           onBlur={() => this.exitInputMode()}