BREAKING CHANGE: This change slightly alters the default positioning
of GlDisclosureDropdown and GlListbox.

If the dropdown is placed inside a <main> element: The disclosure
will use main as a boundary to not overflow it. This change aims
to smartly reduce the need to use custom "placement" ('right'
and 'bottom-end') options, especially when the dropdown is placed
on the right side, such as in contextual menus.

If the dropdown is not placed in a <main> element, behavior does
change.

test(GlSkeletonLoader): add a11y tests

Closes #2520

See merge request gitlab-org/gitlab-ui!4112



Merged-by: Lukas 'ai-pi' Eipert <leipert@gitlab.com>
Approved-by: Lukas 'ai-pi' Eipert <leipert@gitlab.com>
Co-authored-by: Chandra Kiran G <chandrakiran.g19@gmail.com>

feat(BaseDropdown): Use a "main" element boundary when available

Closes #2588

See merge request gitlab-org/gitlab-ui!4095



Merged-by: Paul Gascou-Vaillancourt <pgascouvaillancourt@gitlab.com>
Approved-by: Paul Gascou-Vaillancourt <pgascouvaillancourt@gitlab.com>
Approved-by: Florie Guibert <fguibert@gitlab.com>
Approved-by: Jeremy Elder <jelder@gitlab.com>
Reviewed-by: Paul Gascou-Vaillancourt <pgascouvaillancourt@gitlab.com>
Reviewed-by: Sascha Eggenberger <seggenberger@gitlab.com>
Co-authored-by: Miguel Rincon <mrincon@gitlab.com>

# [79.0.0](gitlab-org/gitlab-ui@v78.19.0...v79.0.0) (2024-04-22)

### Features

* **BaseDropdown:** Use a "main" element boundary when available ([ee0cd82b](gitlab-org/gitlab-ui@ee0cd82b))

### BREAKING CHANGES

* **BaseDropdown:** This change slightly alters the default positioning
of GlDisclosureDropdown and GlListbox.

If the dropdown is placed inside a <main> element: The disclosure
will use main as a boundary to not overflow it. This change aims
to smartly reduce the need to use custom "placement" ('right'
and 'bottom-end') options, especially when the dropdown is placed
on the right side, such as in contextual menus.

If the dropdown is not placed in a <main> element, behavior does
change.