Draft: doc: generate -dev openapis

What

Currently, only the OpenAPIs of the last released version (candidate) of Octez are published in the doc.

This MR proposes to also publish the latest development versions, that is:

• the master version of the Octez node shell RPCs
• the Alpha version of the Octez node protocol RPCs
• the Alpha version of the smart rollup node RPCs
• the master version of the DAL node RPCs

Why

RPCs for Alpha are currently available in static RPC pages (*/*rpc.rst) but not in OpenAPI format.

In turn, static RPCs include the master version but not the latest (stable or candidate) release.

How

Optionally generate *-dev OpenAPIs int the documentation Makefile by running the generation script, and include the generated files in page api/openapi.rst.

Manually testing the MR

Check the additions in the OpenAPI page, in the doc artifact. The links to the generated files don't work yet, they'll only work once the MR is merged.

Then generate the dev OpenAPIs locally, with make -C docs openapi and check whether this modifies the version registered under git, with git status. This won't be the case here, unless you rebase the MR on the latest master, in which case, they may possibly differ. If they do, you could add the changed files in a new commit, in this MR or in a separate MR.

Checklist

• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR