refact: remove linux headless (#15866)

* refact: remove linux headless

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(linux): probe DRM availability asynchronously on login

Signed-off-by: fufesou <linlong1266@gmail.com>

* revert changes in drm_capturer.rs

Signed-off-by: fufesou <linlong1266@gmail.com>

* Update submodule hbb_common

Signed-off-by: fufesou <linlong1266@gmail.com>

* docs(linux): clarify DRM availability comments

Remove stale headless and unauthenticated-request
wording, and document the Available-only login-screen gate.

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(linux): remove unreachable session cleanup branch

Remove the obsolete empty-session path and
clarify the intended use of cached DRM availability.

Signed-off-by: fufesou <linlong1266@gmail.com>

---------

Signed-off-by: fufesou <linlong1266@gmail.com>

appimage/AppImageBuilder-aarch64.yml

@@ -58,7 +58,6 @@ AppDir:
     - libpulse0
     - packagekit-gtk3-module
     - libcanberra-gtk3-module
-    - libpam0g
     - libdrm2
     exclude:
     - humanity-icon-theme

appimage/AppImageBuilder-x86_64.yml

@@ -61,7 +61,6 @@ AppDir:
     - libpulse0
     - packagekit-gtk3-module
     - libcanberra-gtk3-module
-    - libpam0g
     - libdrm2
     exclude:
     - humanity-icon-theme