fixed-needs-triage-issue of code-#31341

[devtanish]

This PR updates all usages of Angular Material button directives from the deprecated kebab-case format to the new camelCase format introduced in Angular Material v20.

🔧 Changes Made
Replaced all instances of mat-button with matButton
Replaced mat-raised-button with matRaisedButton
Replaced mat-flat-button with matFlatButton
Replaced mat-stroked-button with matStrokedButton
Replaced mat-icon-button with matIconButton

Issue code :- #31341

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[crisbeto]

There are lots of incorrect changes here. At a glance:

• Changelog shouldn't be touched.
• Usages of mat-button-toggle were wrongly renamed.
• Names of CSS tokens were changed.