Improve cross-package linking in iov-core

[ethanfrey]

tsdoc generation is nice, but works best when rendering in one package of the mono-repo.

Many times, references to Types that are defined in other packages within the mono-repo do not render as links, such as the faucet: https://iov-one.github.io/iov-core-docs/latest/iov-faucets/classes/bovfaucet.html#credit (no link to TokenTicker).

It is possible to pull in all these types and render all the links using a different config. We can see this pulled in @iov/core docs Linked to from one type: https://iov-one.github.io/iov-core-docs/latest/iov-core/interfaces/bcpcoin.html#tokenticker Present in globals: https://iov-one.github.io/iov-core-docs/latest/iov-core/globals.html#tokenticker

Unfortunately, when I was tuning tsdoc, I found a way to focus on one package, or pull in types from all of them (including many external ones like libsodium). If we can only pull in type definitions that are directly imported from the rendered package, ideall linking to the docs for the other package, that would be ideal. Either I need to dig in deeper to the config or add code to tsdoc to enable such custom functionality.