add Matrix & unit types, update generate mjml file to use Matrix type

[hchiufaire]

Addresses #24.

• added types for px, %, and em, as well as Matrix which type-supports 1-4 values for css shorthands
  (i.e. padding: 0 10% 6em 4px;)
  • updated MJML component script to use Matrix when parsing {1,4} from MJML types (example from source), with appropriate units (px, %, em)
  • single value props are also changed to Pixel, Percentage, Ephemeral types where possible
• updated imports on script template and regenerated components

Note: typically the only unit-less number you can have as a CSS prop is "0", so the new type definition of allowing any number without a unit is not as strict as it could be, but props like flex accept other unit-less numbers than "0", so this can be addressed later on in cases if needed

Updated Tests

New Type Checking in Web-Email-Server (after yarn link)

[hchiufaire]

@IanEdington I updated the types for all props, not just those that use shorthand/Matrix, so there are a lot more changed props as you were expecting now