Schematic hierarchy navigator: remember tree state; expand tree by default

Description

The hierarchy navigator currently always starts collapsed. It would be more useful for most schematics to start with the tree fully expanded. Either way, it would be nice to save the state in the project local settings.

KiCad Version

Application: KiCad Schematic Editor arm64 on arm64

Version: 8.0.7, release build

Libraries:
	wxWidgets 3.2.6
	FreeType 2.13.2
	HarfBuzz 8.3.0
	FontConfig 2.15.0

Platform: macOS Sonoma Version 14.4.1 (Build 23E224), 64 bit, Little endian, wxMac
OpenGL: Apple, Apple M1 Pro, 2.1 Metal - 88

	wxWidgets: 3.2.6 (wchar_t,wx containers)
	Boost: 1.84.0
	OCC: 7.7.2
	Curl: 7.87.0
	ngspice: 42
	Compiler: Clang 14.0.3 with C++ ABI 1002

Build settings: