feat(SpectralSolver): Spectral Solver now works in a limited fashion

Major work on spectral solver, can now evolve up to about a year. At
that point we likely need to impliment repartitioning logic to stabalize
the network or some other scheme based on the jacobian structure

tests/graphnet_sandbox/meson.build

@@ -4,8 +4,8 @@ executable(
     dependencies: [gridfire_dep, cli11_dep],
 )
 
-#executable(
-#    'spectral_sandbox',
-#    'spectral_main.cpp',
-#    dependencies: [gridfire_dep, cli11_dep]
-#)
+executable(
+    'spectral_sandbox',
+    'spectral_main.cpp',
+    dependencies: [gridfire_dep, cli11_dep]
+)