frontend: Fix user config subfolder creation

[Warchamp7]

Description

Fixes OBS failing to launch when Configuration in global.ini is set to a folder that exists but does not have an obs-studio subfolder inside it.

Motivation and Context

global.ini allows the configuration of four different paths:

[Locations]
Configuration=
SceneCollections=
Profiles=
PluginManagerSettings=

All of these locations are used as a base path and anything using them places files into <base>/obs-studio/

SceneCollections, Profiles, and PluginManagerSettings all ensure that the obs-studio subfolder exists.
Configuration does not.

As a result OBS will fail to create it's user.ini file during startup and immediately close.

How Has This Been Tested?

• Set paths of all Locations to a folder that does not exist

  • OBS falls back to the default locations and launches with my normal settings, stored in appdata

• Set paths of all Locations to a folder that does exist but with no obs-studio subfolder

  • OBS cannot create user.ini and fails during startup

• Created obs-studio folder manually in the specified location

  • OBS launches successfully and creates all data in the specified location

• Set Configuration to it's default AppData location but changed the others to a custom folder

  • OBS launches using normal user.ini, all other locations correctly set up obs-studio subfolders

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.