[ts-sdk] generate TS type guards (replace superstruct)

[stella3d]

created this branch to show another approach that allows eliminating the superstruct boilerplate and keeping standard TS definitions. This works better with Intellisense, eliminates the dual type declarations, allows us to embed just the guard functions instead of the superstruct lib.

This approach auto-generates type guards for the project at build time.

[666lcz]

Love this! Did not know that there's a type guard generator. This seems to be an overall better solution than superstruct. The only downside is with superstruct is easier to debug which field is wrong while type guard only gives you a boolean.

[stella3d]

updated to add license headers to generated files