Official devcontainer config

Stack Overflow 2024 developer survey[1] said VSCode
is the most used development environment.

In a PostgreSQL Hacker Mentoring discussion, we talked
about how to use vscode to debug and running postgres,
Andrey(ccd) has tons of tips for new developers, and
I post my daily used devcontainer config[2] , Jelte(ccd)
suggested that it might be a good idea we integrate the
config into postgres repo so that the barrier to entry for
new developers will be much lower.

**Note**

This is not intended to change the workflow of experienced
hackers, it is just hoping to make the life easier for
beginner developers.

**How to use**

Open VSCode Command Palette(cmd/ctrl + shift + p),
search devcontainer, then choose something like
`Dev containers: Rebuild and Reopen in Container`, you are
good to go.

**About the patch**

devcontainer.json:

The .devcontainer/devcontainer.json is the entry point for
VSCode to *open folder to develop in a container*, it will build
the docker image for the first time you open in container,
this will take some time.

There are some parameters(runArgs) for running the container,
we need some settings and privileges to run perf or generate
core dumps.

It has a mount point mapping the hosts $HOME/freedom
to container's /opt/freedom, I chose the name *freedom*
because the container is kind of a jail.

It also installed some vscode extensions and did some
customizations.

After diving into the container, the postCreateCommand.sh
will be automatically called, it will do some configurations
like git, perf, .vscode, core_pattern, etc. It also downloads
michaelpq's pg_plugins and FlameGraph.

Dockerfile:

It is based on debian bookworm, it installed dependencies
to build postgres, also IPC::Run to run TAP tests I guess.

It also has a .gdbinit to break elog.c:errfinish for elevel 21,
this will make the debugging easier why error is logged.

gdbpg.py is adapted from https://github.com/tvondra/gdbpg,
I think putting it here will make it evolve as time goes.

tasks.json:

This is kind of like a bookkeeping for developers, it has
the following commands:

- meson debug setup
- meson release setup
- ninja build
- regression tests
- ninja install
- init cluster
- start cluster
- stop cluster
- install pg_bsd_indent
- pgindent
- apply patch
- generate flamegraph

launch.json:

It has one configuration that makes it possible to attach
to one process(e.g. postgres backend) and debug
with vscode.

PFA and please give it a try if you are a VSCode user.

[1]: https://survey.stackoverflow.co/2024/technology#1-integrated-development-environment
[2]: https://github.com/atomicdb/devcontainer/tree/main/postgres

--
Regards
Junwang Zhao