Remove hardcoded default worksheet and make new projects reference the .kicad_wks installed with KiCad
Description
Spun out from #5420 (closed)
Currently the default worksheet is "hardcoded". If the page layout file field in page settings is empty, it shows the (hardcoded) default. Changing the default would change the display of every existing schematic and board file that doesn't specify the worksheet (which is probably most of them) and would probably be considered undesirable.
Ideally, no worksheet means no worksheet (blank). If a new project is created, the field should be pre-populated to point at the default installed with KiCad. This would be a change in behaviour and require converting old projects.
There could be a setting in preferences to set the default worksheet for new projects, since there is a range of worksheet designs available in the KiCad install (or a users/organisations own).
This would have the positive side effect of removing the blank worksheet hack for imported projects.
Steps to reproduce
KiCad Version
Application: KiCad
Version: (5.1.7-0-10_14), release build
Libraries:
wxWidgets 3.0.4
libcurl/7.64.1 SecureTransport (LibreSSL/2.8.3) zlib/1.2.11 nghttp2/1.39.2
Platform: macOS Catalina Version 10.15.6 (Build 19G2021), 64 bit, Little endian, wxMac
Build Info:
wxWidgets: 3.0.4 (wchar_t,STL containers,compatible with 2.8)
Boost: 1.72.0
OpenCASCADE Community Edition: 6.9.1
Curl: 7.54.0
Compiler: Clang 9.0.0 with C++ ABI 1002
Build settings:
USE_WX_GRAPHICS_CONTEXT=ON
USE_WX_OVERLAY=ON
KICAD_SCRIPTING=ON
KICAD_SCRIPTING_MODULES=ON
KICAD_SCRIPTING_PYTHON3=OFF
KICAD_SCRIPTING_WXPYTHON=ON
KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
KICAD_SCRIPTING_ACTION_MENU=ON
BUILD_GITHUB_PLUGIN=ON
KICAD_USE_OCE=ON
KICAD_USE_OCC=OFF
KICAD_SPICE=ON