Re-implement ``<form>`` to add colors

Milestone v2 includes the restructuring of the codebase. This might mean making some code obsolete by introducing another library as dependency or re-implementing existing code in TypeScript (to leverage the benefits of type safety and syntactic sugar).

Features

[x] ColorizerForm
- [x] setup the input methods; controlled by an argument during instance creation
- [x] submit callback; controlled by an argument during instance creation
- [x] keep track of the current color and expose it (getColor())
[x] input method RGB
[x] input method OkLCH

Why is the `<form>` logic the first refactoring subject?

This comment includes an experimental, VanillaJS re-implementation of the <form> logic. It is sufficiently complex to verify that the TS setup (#16) is working ~~and the implementation will be one place, where the (external) color libraries (see #10) can be evaluated~~.

[repo_root]
├── src/
│   ├── script/
│   |   ├── colorizer/
|   │   |   ├── interface/
|   |   │   |   ├── color_form/
|   |   |   │   |   ├── input_methods.ts
|   |   |   │   |   ├── form.ts
|   |   |   |   │   └── index.ts
|   |   │   |   ├── grid_view.ts
|   |   │   |   ├── palette.ts
|   |   |   │   └── index.ts
|   │   |   ├── engine.ts
|   |   │   └── index.ts
│   |   ├── utility/
|   |   │   └── index.ts
|   │   └── index.ts
│   └── style/   <-- details in #18 
└── tsconfig.json

Mischback / colorizer