Re-enable using non-officially-supported generators when building with MSVC

Signed-off-by: Chris Burel <burelc@amazon.com>

cmake/Platform/Common/MSVC/Configurations_msvc.cmake

@@ -6,13 +6,15 @@
 #
 #
 
+set(minimum_supported_toolset 142)
+if(MSVC_TOOLSET_VERSION VERSION_LESS ${minimum_supported_toolset})
+    message(FATAL_ERROR "MSVC toolset ${MSVC_TOOLSET_VERSION} is too old, minimum supported toolset is ${minimum_supported_toolset}")
+endif()
+unset(minimum_supported_toolset)
+
 include(cmake/Platform/Common/Configurations_common.cmake)
 include(cmake/Platform/Common/VisualStudio_common.cmake)
 
-if(NOT CMAKE_GENERATOR MATCHES "Visual Studio 1[6-7]")
-    message(FATAL_ERROR "Generator ${CMAKE_GENERATOR} not supported")
-endif()
-
 # Verify that it wasn't invoked with an unsupported target/host architecture. Currently only supports x64/x64
 if(CMAKE_VS_PLATFORM_NAME AND NOT CMAKE_VS_PLATFORM_NAME STREQUAL "x64")
     message(FATAL_ERROR "${CMAKE_VS_PLATFORM_NAME} target architecture is not supported, it must be 'x64'")
@@ -114,14 +116,6 @@ else()
     )    
 endif()
 
-if(CMAKE_GENERATOR MATCHES "Visual Studio 15")
-    # Visual Studio 2017 has problems with [[maybe_unused]] on lambdas. Sadly, there is no different warning, so 4100 has to remain disabled on 2017
-    ly_append_configurations_options(
-        COMPILATION
-            /wd4100
-    )
-endif()
-
 # Configure system includes
 ly_set(LY_CXX_SYSTEM_INCLUDE_CONFIGURATION_FLAG 
     /experimental:external # Turns on "external" headers feature for MSVC compilers

scripts/build/Platform/Windows/package_build_config.json

@@ -1,15 +1,4 @@
 {
-  "profile_vs2017_atom": {
-    "COMMAND": "build_windows.cmd",
-    "PARAMETERS": {
-      "CONFIGURATION": "profile",
-      "OUTPUT_DIRECTORY": "windows_vs2017",
-      "CMAKE_OPTIONS": "-G \"Visual Studio 15 2017\" -A x64 -T host=x64 -DCMAKE_SYSTEM_VERSION=10.0 -DLY_UNITY_BUILD=TRUE",
-      "CMAKE_LY_PROJECTS": "AtomTest;AtomSampleViewer",
-      "CMAKE_TARGET": "ALL_BUILD",
-      "CMAKE_NATIVE_BUILD_ARGS": "/m:4 /p:CL_MPCount=!HALF_PROCESSORS! /nologo"
-    }
-  },
   "profile_vs2019_atom": {
     "COMMAND":"build_windows.cmd",
     "PARAMETERS": {