fix(@angular/cli): exclude @angular/material@7.x from ng add package discovery

`@angular/material@7.x` uses unbounded ranges for its framework peer dependencies.
This can cause `ng add` to pick these versions of the package if the newer versions
are not compatible since the peer dependency ranges would match any newer stable
framework version.

(cherry picked from commit 9260087)

Author: clydin

packages/angular/cli/src/commands/add/cli.ts

@@ -50,6 +50,8 @@ interface AddCommandArgs extends SchematicsCommandArgs {
 const packageVersionExclusions: Record<string, string | undefined> = {
   // @angular/localize@9.x versions do not have peer dependencies setup
   '@angular/localize': '9.x',
+  // @angular/material@7.x versions have unbounded peer dependency ranges (>=7.0.0)
+  '@angular/material': '7.x',
 };
 
 export class AddCommandModule