Restructure directories and packages

[GewoonMaarten]

Currently, if you install the root package you'll get all components three times. This is because of the nested package structure we currently have. This is not desirable. In addition, component's .tsx files are provided as is, meaning that the developer who installs the components gets the raw .tsx files. Usually you want to transpile the ts to js and provide a Typescript type file and/or transpile esx to es2017, which 90% of the browser support. This way developers can use both Javascript and Typescript.

Tasks:

• Flatten the directory structure such that every component is directly in the src/components directory. The group components like surfaces and input can be moved to src/groups (for example) for clarity as their only purpose is to group components.
• consolidate some components into one package as it makes little sense to use one without the other:
  • Components into tab
    • tab
    • tabcontext
    • tablist
    • tabpanel
    • tabs
    • tabscrollbutton
  • Components into menu
    • menuitem
    • menulist
    • popover
    • popper
  • Components into list
    • listitem
    • listitemavatar
    • listitemicon
    • listitemsecondaryaction
    • listitemtext
    • listsubheader
  • Components into avatar
    • avatargroup
  • Components into card
    • cardactions
    • cardcontent
    • cardheader
    • paper
  • Components into accordion
    • accordionactions
    • accordiondetails
    • accordionsummary
• Create an index.tsx files when needed.
• Fix installed package files. TBD
• Test if components install correctly.

[bddjong]

Scoped to only flattening the directory structure