Angular Material 15 code changes

The @angular/material source changes of the version 15 migration. Imports stay on the MDC-based components rather than the deprecated legacy-* entry points that Material 17 removed. Templates and styles move to those components as the mdc-migration schematic does: chips, slider, form field appearances, typography classes, renamed class selectors and the themes the components rely on. It finds the rest: list directives, the tab nav bar panel, form field labels, removed exports and members, custom snack bar content, themes built from palette maps without define-palette, and constructor calls that no longer fit. UpgradeToAngular15 includes this recipe.