WIP Patch: pg_dump structured

Hi all,

I was looking for a way to track actual schema changes after database migrations
in a VCS. Preferably, the schema definition should come from a trusted source
like pg_dump and should consist of small files.
This patch was born out of that need.

This patch adds the structured output format to pg_dump.
This format is a plaintext output split up into multiple files and the
resulting small files are stored in a directory path based on the dumped object.
This format can be restored by feeding its plaintext toc file (restore-dump.sql)
to psql. The output is also suitable for manipulating the files with standard
editing tools.

This patch is a WIP (V1). The patch is against master and it compiles
successfully on macOS 13.2.1 aarch64 and on Debian 11 arm64.
To test, execute pg_dump --format=structured --file=/path/to/outputdir dbname

What do you think of this feature, any chance it will be added to pg_dump once
the patch is ready?
Is the chosen name "structured" appropriate?

Thanks for any feedback.

--
Attila Soki