Build a theme generator/picker that simplifies the process

#### Bug, feature request, or proposal:
Feature Request

#### What is the current behavior?
Custom theming angular material is cumbersome.

#### What is the use-case or motivation for changing an existing behavior?
Make it easier to modify theme based on more traditional number color palettes. Designers will often provide 3-6 colors that should encompass most of the application/website, while the material pallets have over a dozen color hues per palette, for a total of well over 50 colors that the app can use. This isn't practical to maintain unless one REALLY cares about each shade. I understand the Ng Material team is just using the official Material colors but in my opinion there is a balance to be struck.

Maybe I'm missing something from the docs but I really would prefer not to do:
$candy-app-primary: mat-palette($mat-indigo); // this palette has over dozen colors to maintain

and instead do
$candy-app-primary: mat-palette(#999); // where 999 is my primary color

And have the material theme generate the variants in some way OR do it like Bootstrap and use scss lightens/darkens mixins where appropriate.

Suggestion:
Incorporate a palette generator of some kind, perhaps using similar logic as used by the material tool.
https://material.io/design/color/the-color-system.html#tools-for-picking-colors

現在の Angular Material の theming ドキュメントと、issue で説明されている mat-palette の使用方法を確認し、提案されたワークフローをリンク先の Material color-system ツールと比較してください。picker または generator が少数の色を受け取り、使用可能なテーマバリアントを生成する方法を定義してください。このワークフローが仕様化され、適切なドキュメントによってサポートされた時点で作業完了です。

索引モデルが issue の本文から書いたものです。