CMakePresets.json: Make --list-presets show presets with no generator

Fixes: #22389

Source/cmake.cxx

@@ -1687,6 +1687,9 @@ void cmake::PrintPresetList(const cmCMakePresetsFile& file) const
   this->GetRegisteredGenerators(generators, false);
   auto filter =
     [&generators](const cmCMakePresetsFile::ConfigurePreset& preset) -> bool {
+    if (preset.Generator.empty()) {
+      return true;
+    }
     auto condition = [&preset](const GeneratorInfo& info) -> bool {
       return info.name == preset.Generator;
     };

Tests/RunCMake/CMakePresets/ListPresets-stdout.txt

@@ -1,6 +1,7 @@
 ^Not searching for unused variables given on the command line\.
 Available configure presets:
 
-  "zzzzzz"   - Sleepy
-  "aaaaaaaa" - Screaming
-  "mmmmmm"$
+  "zzzzzz"       - Sleepy
+  "aaaaaaaa"     - Screaming
+  "mmmmmm"
+  "no-generator"$

Tests/RunCMake/CMakePresets/ListPresets.json.in

@@ -1,5 +1,5 @@
 {
-  "version": 1,
+  "version": 3,
   "configurePresets": [
     {
       "name": "zzzzzz",
@@ -18,6 +18,9 @@
       "generator": "@RunCMake_GENERATOR@",
       "binaryDir": "${sourceDir}/build/mmmmmm"
     },
+    {
+      "name": "no-generator"
+    },
     {
       "name": "invalid-generator",
       "generator": "Invalid Generator",

Tests/RunCMake/CMakePresets/ListPresetsHidden-stdout.txt

@@ -1,6 +1,7 @@
 ^Not searching for unused variables given on the command line\.
 Available configure presets:
 
-  "zzzzzz"   - Sleepy
-  "aaaaaaaa" - Screaming
-  "mmmmmm"$
+  "zzzzzz"       - Sleepy
+  "aaaaaaaa"     - Screaming
+  "mmmmmm"
+  "no-generator"$

Tests/RunCMake/CMakePresets/ListPresetsNoSuchPreset-stdout.txt

@@ -1,6 +1,7 @@
 ^Not searching for unused variables given on the command line\.
 Available configure presets:
 
-  "zzzzzz"   - Sleepy
-  "aaaaaaaa" - Screaming
-  "mmmmmm"$
+  "zzzzzz"       - Sleepy
+  "aaaaaaaa"     - Screaming
+  "mmmmmm"
+  "no-generator"$

Tests/RunCMake/CMakePresets/ListPresetsWorkingDir-stdout.txt

@@ -1,6 +1,7 @@
 ^Not searching for unused variables given on the command line\.
 Available configure presets:
 
-  "zzzzzz"   - Sleepy
-  "aaaaaaaa" - Screaming
-  "mmmmmm"$
+  "zzzzzz"       - Sleepy
+  "aaaaaaaa"     - Screaming
+  "mmmmmm"
+  "no-generator"$