Add permission for Flatpak.

[istori1]

Description

Adding --talk-name=org.freedesktop.Flatpak as this is needed to launch applications on the host. Example: flatpak-spawn --host sleep 1m.

Screenshot

Issues Fixed or Closed

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the docstring/documentation-blocks for new or existing methods/components

[CLAassistant]

All committers have signed the CLA.

[ReenigneArcher]

Is any documentation update needed for this?

[istori1]

We should document using "flatpak-spawn --host app/game executable"

[ReenigneArcher]

We should document using "flatpak-spawn --host app/game executable"

Perhaps it should be defined in this section? https://github.com/istori1/Sunshine/blob/patch-2/docs/source/about/usage.rst#application-list

OR https://github.com/istori1/Sunshine/blob/patch-2/docs/source/troubleshooting/linux.rst#linux

[istori1]

We should document using "flatpak-spawn --host app/game executable"

Perhaps it should be defined in this section? https://github.com/istori1/Sunshine/blob/patch-2/docs/source/about/usage.rst#application-list

OR https://github.com/istori1/Sunshine/blob/patch-2/docs/source/troubleshooting/linux.rst#linux

It should be in the usage section.