Add EXTRA_PATH ext to PATH env

[jcleng]

add EXTRA_PATH from user flatpak env , ext to apps PATH
#419

for example python pip need ~/.local/bin/ for other expansions.

[flathubbot]

Started test build 61097

[flathubbot]

Build 61097 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/43734/com.visualstudio.code.flatpakref

[flathubbot]

Started test build 66311

[flathubbot]

Build 66311 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/48968/com.visualstudio.code.flatpakref