The application migration schematic will now attempt to detect the usage
of custom postcss plugins within a workspace and install the `postcss` dependency
if required. This will only occur if the migration analysis allows for
the conversion to use the `@angular/build` package instead of the
`@angular-devkit/build-angular` package. Custom postcss configurations will
be detected within the same locations as the build system itself which includes
the workspace root and any project root for the `postcss.config.json` and
`.postcssrc.json` files.
The application migration schematic will now attempt to detect the usage
of Less stylesheets within a workspace and install the `less` dependency
if required. This will only occur if the migration analysis allows for
the conversion to use the `@angular/build` package instead of the
`@angular-devkit/build-angular` package. The Less usage detection may
not detect Less stylesheets within Node.js packages and currently does
not handle the case where a project only has inline Less stylesheets.
More complex analysis may be added in the future. However, a build time
error message will be presented with instructions to install `less` in
these cases if the stylesheet preprocessor is required and not present.
