RFE: unvendor `pydevd` module or update it to latest version

[kloczek]

Looks like pydevd is well maintained and has regilar new releases.
Is it any reason why this module is bundled in debugpy tree?

[rchiodo]

I believe the reason it's bundled is so we can ship debugpy with Visual Studio and VS code without having the user install any packages. @karthiknadiq or Pavel Minaev (@int19h) may know more.

Transferring this to a discussion.