refactor: use the external `dealfilter` go module

[nicobao]

EDIT: see #609 (comment) . I suggest to move the dealfilter component in a separate repo (only the types that generate the JSON).

Current situation

Third-parties that want to integrate with the boost's output have to manually check deal proposals JSON structure from the Go codebase or by asking the boost team: #497 (comment)
Then they have to write the tools to validate the JSON structure themselves. It's especially harder if the third-party doesn't use golang.

Challenge

It would be nice to provide a JSON Schema of the possible Boost outputs for each Boost future versions, to make it easier and safer for tools integrating with boost.
It would also serve as documentation.

Proposed changes

• Enable the generation of a JSON from the Go types that ultimately generates JSON files:

  boost/storagemarket/dealfilter/cli.go

  Line 18 in d4f4d3f

  func CliStorageDealFilter(cmd string) dtypes.StorageDealFilter {

  and

  boost/storagemarket/dealfilter/cli.go

  Line 35 in d4f4d3f

  func CliRetrievalDealFilter(cmd string) dtypes.RetrievalDealFilter {

• Enable the generation of a Go library to parse and validate the boost JSON outputs
• Improve CI/build workflow to do this automatically at each bump to a new Boost release - and make the new JSON Schema/go library available at the same time as the release

[nicobao]

Hi,
This is still on my agenda, I was just too busy to work on it.

[nicobao]

For info, some work is currently being done here: https://github.com/CIDgravity/dealfilter
I will send a PR for Boost to use the separate module later. In the meantime, feel free to reach out to me.
The rationale for creating a separate repository is the following:

• the boost repo is not organized as a go workspace. Publishing a separate go module for the dealfilter is not possible without non-trivial refactoring.
• many different teams (Venus, Boost, CIDgravity, Forest?) might be interested in contributing to the deal-filter type description

My idea is to hand over the repository to the filecoin-project organization.