fix(menu): improve reliability of main content not being scrollable when menu opens (#28829)

Issue number: resolves #28399

---------

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## What is the current behavior?
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As part of https://github.com/ionic-team/ionic-framework/pull/26976 I
fixed an issue where `pointer-events: none` was not applied until after
the menu open gesture finishes. This resolved a bug where scrolling was
latching after the menu gesture starts.

However, I did not account for the edge case where scrolling latches
_before_ `pointer-events: none` is applied in the DOM. Since scrolling
has already latched then `pointer-events: none` does not change the
scrolling behavior. This can happen if a user swipes up and to the right
from the left edge of the screen.

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

- `overflow-y: hidden` is now applied to the scrollable content which
will interrupt any scrolling when the menu is open.

## 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. -->


Testing:

This bug fixes a timing issue where scrolling latches on the main
content as the menu tries to open. As a result, I am unable to write
reliable automated tests for this. Reviewers should perform the
following test on iOS and Android physical devices:

1. Open `src/components/menu/test/basic`.
2. Add enough elements to the main page content such that it scrolls (I
added a list with items).
3. On each device, attempt to scroll the main content while also opening
the menu on the starting edge of the screen.

Scrolling on the main content should not happen if the menu opens.

Dev build: `7.6.5-dev.11705341148.1a550d3b`

core/src/css/core.scss

@@ -250,9 +250,36 @@ ion-card-header.ion-color .ion-inherit-color {
   cursor: pointer;
   touch-action: manipulation;
 
-  // the containing element itself should be clickable but
-  // everything inside of it should not clickable when menu is open
+  /**
+   * The containing element itself should be clickable but
+   * everything inside of it should not clickable when menu is open
+   *
+   * Setting pointer-events after scrolling has already started
+   * will not cancel scrolling which is why we also set
+   * overflow-y below.
+   */
   pointer-events: none;
+
+  /**
+   * This accounts for scenarios where the main content itself
+   * is scrollable.
+   */
+  overflow-y: hidden;
+}
+
+/**
+ * Setting overflow cancels any in-progress scrolling
+ * when the menu opens. This prevents users from accidentally
+ * scrolling the main content while also dragging the menu open.
+ * The code below accounts for both ion-content and then custom
+ * scroll containers within ion-content (such as virtual scroll)
+ */
+.menu-content-open ion-content {
+  --overflow: hidden;
+}
+
+.menu-content-open .ion-content-scroll-host {
+  overflow: hidden;
 }
 
 .ios .menu-content-reveal {