[sdl1] Change the extension of the template MSBuild solution. (#31685)

* [sdl1] Change the extension of the template MSBuild solution.
It will prevent Visual Studio from suggesting to open it, if you have opened a project using vcpkg as a directory.

* Update version database.

ports/sdl1/portfile.cmake

@@ -13,7 +13,7 @@ vcpkg_from_github(
 configure_file("${SOURCE_PATH}/include/SDL_config.h.default" "${SOURCE_PATH}/include/SDL_config.h" COPYONLY)
 
 if(VCPKG_TARGET_IS_WINDOWS AND NOT VCPKG_TARGET_IS_MINGW)
-    file(COPY "${CMAKE_CURRENT_LIST_DIR}/SDL1_2017.sln" DESTINATION "${SOURCE_PATH}/VisualC/")
+    configure_file("${CURRENT_PORT_DIR}/SDL1_2017.sln.in" "${SOURCE_PATH}/VisualC/SDL1_2017.sln" COPYONLY)
 
     if(VCPKG_LIBRARY_LINKAGE STREQUAL "static")
         set(LIB_TYPE StaticLibrary)

ports/sdl1/vcpkg.json

@@ -1,7 +1,7 @@
 {
   "name": "sdl1",
   "version": "1.2.15",
-  "port-version": 17,
+  "port-version": 18,
   "description": "Simple DirectMedia Layer is a cross-platform development library designed to provide low level access to audio, keyboard, mouse, joystick, and graphics hardware via OpenGL and Direct3D.",
   "homepage": "https://www.libsdl.org",
   "license": "LGPL-2.1-or-later",

versions/baseline.json

@@ -7310,7 +7310,7 @@
     },
     "sdl1": {
       "baseline": "1.2.15",
-      "port-version": 17
+      "port-version": 18
     },
     "sdl1-mixer": {
       "baseline": "2023-03-25",

versions/s-/sdl1.json

@@ -1,5 +1,10 @@
 {
   "versions": [
+    {
+      "git-tree": "5463be881042b7d98bf14377bb790a2a83c3a39e",
+      "version": "1.2.15",
+      "port-version": 18
+    },
     {
       "git-tree": "45b686784ad1b01e7cfa7988bc3f95bf9aff6b6a",
       "version": "1.2.15",