flet/client for Linux: rename main binary from flet to flet_runner

[lucasew]

Please Describe The Problem To Be Solved
I am one of the maintainers of this package in nixpkgs. IMO the packaging now is very complete. I was the one that added the client to nixpkgs but there is a small annoying issue: both the client and the python library expose the flet command.

(Optional): Suggest A Solution

Just rename the main binary of the client from flet to flet_client. I think it can be done changing that binary name in CMakeLists.txt. It would need to also be changed in the code so Python knows how to launch the client.

If you guys for some reason don't care, a Nix-only fix wouldn't be hard too. A mv in a postInstall phase and a change in meta.mainProgram would give the same results without risk of breakage in your side.

[FeodorFitsner]

That makes sense. Will keep that in mind for next releases.

[FeodorFitsner]

I'm going to do that for 0.24 or 0.25 release as part of #3163.

I suggest we name it flet_runner though. I don't like this old "Flet client" name, because it's no longer a client :)