Build Script For Exporting Compile Commands

[Bixkitts]

I wanted to look at this in Neovim.
The clangd language server needs a compile_commands.json to function.
One can be created with pio run -t compiledb but it's incomplete
and doesn't include toolchain/std libraries properly without the
python script: https://docs.platformio.org/en/stable//integration/compile_commands.html

Figured it would be harmless to make a PR to help other LSP users
cloning this.

[github-actions]

Thanks @Bixkitts 🏆

[xyzroe]

Could you also update readme - add section how to build using Neovim ?

[Bixkitts]

Sure I'll add a section about building from the CLI and getting a compilation DB for custom language server setup (neovim users, for example)