refactor(ui5-menu): rename the busy and busy delay properties

[unazko]

Renames the busy and busyDelay properties of the ui5-menu and ui5-menu-item to loading and loadingDelay.

BREAKING CHANGE: The busy and busyDelay and properties of the ui5-menu and ui5-menu-item are renamed.
If you have previously used the busy, busyDelay properties:

<ui5-menu header-text="My ui5-menu" busy busy-delay="100"><ui5-menu>

<ui5-menu-item text="Open" icon="open-folder" busy busy-delay="100"><ui5-menu-item>

now you should use loading and loadingDelay properties:

<ui5-menu header-text="My ui5-menu" loading loading-delay="100"><ui5-menu>

<ui5-menu-item text="Open" icon="open-folder" loading loading-delay="100"><ui5-menu-item>

Fixes: #8764