For `alert message` component, update to v1.2.0

Descriptions

Verbatims from @TonyAntonyHello:

⚠️ Version 2.7 of the design tokens is required to implement this update.
 
🛠️ Bottom action layout update
We adjusted the layout and spacing around the bottom action:
- Updated the min-height-bottom-action token value from
core-ouds/dimension/1250tocore-ouds/dimension/1000
- Renamed:
dialog/alert/size/min-height-bottom-action-placementtodialog/alert/size/min-height-bottom-action
- Removed the row-gap-action token from the component.
 
📐 Content and asset spacing update
We improved the vertical spacing of the component:
- Added the newouds/dialog/alert/space/padding-block-bottom-content
token to apply bottom padding to the Description and Bullet list.
- Changed the Asset container height to Fill container. Added bottom padding to the Asset container using: ouds/dialog/alert/space/padding-block.
 
🧱 Token architecture update
Some tokens have been reorganised to better reflect where they are used:
- Moved the border-width and row-gap-bullet tokens from the Alert family to the Alert Message family, as they are used exclusively by this component.
- Renamed:
ouds/dialog/alert/size/icon to ouds/dialog/alert/size/asset
The new name reflects that the size is shared by both the icon and the progress indicator.
 
✏️ Component naming update
The “Button” icon only property has been renamed to: Close button
 
📏 Maximum text width
Added the new: ouds/size/max-width/boxed-text
This token defines the maximum width of the text, Description, and Bullet list.

See Figma specification

Definition of Ready

• Implement of tokens v2.7.0 (#868)

Definition of Done

Flutter library

• Update component
• Update CHANGELOG

Design System Toolbox

• Update snapshots
• Update CHANGELOG