This fixes an issue where the app icon would not be visible for
standalone plugin targets.

In cases where no JUCE component had keyboard focus, clicking a menu
item would cause the menu to be dismissed instead of triggering the
item's action.

This comparison can break when relaxing IEEE compliance and enabling
full optimisations.

The main change is that the numFramesToSkipMetalRenderer member has been
removed. The old mechanism had some problems in AU plugins in Logic.
Specifically, when opening a temporary window, repaints would be ignored
until the numFramesToSkipMetalRenderer counter had been decremented to
zero. In practice, this meant that a PopupMenu might not repaint until
the highlighted item had changed five times or more.

With this change applied, repaints that were requested for a particular
window size will use the metal renderer as long as the window hasn't
changed size in the meantime.

AUs are more likely to have 16 channels on a bus now that the 9.1.6
Atmos layout is available.

In some cases, processing key inputs may cause the currently-focused
text input target to be destroyed. If this happens, we shouldn't attempt
to reset the underlining on the target. We now reset the underlining
before processing key presses.

On some platforms, the superclass implementation can throw if it detects
that the preset data is malformed, but it's not clear exactly how the
system determines this.

We now apply only the JUCE state.

Rename look-and-feel method and update docs

- A repaint will always occur from a lookAndFeelChanged

- Created a new detail namespace
- Moved shared module implementation details into the detail namespace
- Split dependencies so source files only rely on details in the detail namespace
- Removed all code from the juce_gui_basics.cpp file

Fixes a bug on Windows when opening a FileChooser with the following
arguments.

    FileChooser ("",
                 "C:\path\to\file", // filename 'file' doesn't contain '.'
                 "",                // all extensions are allowed
                 true);

The expected behaviour is that the initially-displayed filename is
"file".

The actual behaviour was that the initially-displayed filename was
"file.file".