app_server: AppFontManager does not need a BLooper

Saves at least a thread and a few semaphores per app.

Change-Id: Ied43e5944471918b34b897722346a25d159090df
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6073
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

app_server: refactor font managers

Move common add/remove code to the base class and improve encapsulation.
Loading FreeType is the responsibility of the global font manager.
Rename FontManagerBase back to FontManager.

Change-Id: I9396112f01583e19d03011106fd1fa1e37958ee8
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6072
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

app_server: new font code cleanup: includes and the like

Change-Id: I4b7f882fffc34be1984060838f13971c48d4abfc
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6059
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

BFont: allow loading of user fonts from disk or memory

This patch adds an API call to BFont, called LoadFont, that
takes a string path to a font file. The user fonts are managed
via a new class called AppFontManager that inherits from the base
class FontManagerBase but adds the methods to add and remove user
fonts from disk or memory. There is also a new method called UnloadFont
to remove a user font, but on exit of an app all user fonts should be
automatically cleaned up.

Global/system fonts are managed by the GlobalFontManager, which is
a new class that also inherits from the base class FontManagerBase,
replacing the old "FontManager" class.

A maximum of 128 user fonts may be loaded, and memory fonts
may not exceed 20MB.

There's also an overloaded version of LoadFont that accepts
an area_id and loads the font from memory. A size and offset may
optionally be provided to allow for an area that contains more
than just a font.

Change-Id: I6add42bdf0c0cefc0e2e2a4984fd848c3e7269e5
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4790
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>