Move legacy Angular Material styles to the MDC components

Rewrites stylesheets and inline styles in projects that still use the legacy-* components of Material 15 and 16, which Material 17 removed, as the mdc-migration schematic does: replaces the legacy-* mixins with the MDC-based ones, such as mat.legacy-button-theme with mat.button-theme, mat.fab-theme and mat.icon-button-theme, and mat.legacy-core with mat.core, moves mat.define-legacy-typography-config to mat.define-typography-config with the levels of the 2018 type scale, and renames the selectors of classes the MDC components renamed, such as .mat-form-field to .mat-mdc-form-field.