MSVC Builds: Drop Unneeded Defines

...since we are using GLib APIs to locate test data files since
commit b8baa2a0
MSVC Builds: Build the invalid test program

Add project files to build the "invalid" test program.
Visual C++ Builds: Use Custom Build Rules

...so that the json-glib.def file can be regenerated as automatically
when the json-glib.symbols file is updated, and the json-glib.def can be
automatically deleted on a "clean" request.

Also drop some unneeded items from the property sheets.
l10n: Update Japanese translation
path: Check if JSONPath expression is NULL

https://bugzilla.gnome.org/show_bug.cgi?id=708318