Draft initial ethdebug/format/type schema

[gnidan]

• Define ethdebug/format/type as if/then/else

  • if the object is a known kind,
  • then the object must be a known elementary or complex type
  • else the object must be a valid base type with added constraints

• Define ethdebug/format/type/elementary and ethdebug/format/type/elementary/{ uint, int, ufixed, fixed, bool, bytes, string, address, contract, enum }

• Define ethdebug/format/type/complex and ethdebug/format/type/complex/{ alias, tuple, array, mapping, struct }

• Define ethdebug/format/type/wrapper and ethdebug/format/type/reference to serve as more canonical forms that override the base schema equiv.

• Add pages for all the type schemas

• Move "key concepts" from base schema page to own page

• Document schema overall

• Test that all schemas have examples (except for permitted omissions)