feat(material/core): add mixins for Material Design typography

[mikzat]

Angular provides CSS system variables for Material typography, but the variable for "font" is not able to set letter-spacing, which requires users to remember to set letter-spacing separately:

  .mat-font-body-sm {
    font: var(--mat-sys-body-small);
    letter-spacing: var(--mat-sys-body-small-tracking);
  }

This change introduces typography mixins that ensure that both properties are set together, so the above snippet becomes:

  .mat-font-body-sm {
    @include typography.body-small();
  }

End-users can apply these mixins from the mat. entrypoint with a typography- prefix:

  .mat-font-body-sm {
    @include mat.typography-body-small();
  }

[github-actions]

Deployed dev-app for 8d3ba6c to: https://ng-dev-previews-comp--pr-angular-components-32959-dev-w27na8v1.web.app

Note: As new commits are pushed to this pull request, this link is updated after the preview is rebuilt.

[github-actions]

Deployed docs-preview for 8d3ba6c to: https://ng-dev-previews-comp--pr-angular-components-32959-docs-9y7jc320.web.app

Note: As new commits are pushed to this pull request, this link is updated after the preview is rebuilt.