Remove spaces from snippets in the SXNUI (microsoft#17261)

Couple different issues: 
* The suggestions UI can't filter snippets without a name, that have a
space in them, because '␣' != ' '. This instead removes the visualized
space from the name shown in the SXN UI.
* Similarly, we generate an action with leading backspaces to remove the
current commandline. Then we visualize those BS's as a part of the
generated name. Same thing - can't filter to that.


Before in blue: 

![image](https://github.com/microsoft/terminal/assets/18356694/b65e102b-3d23-4d66-9fb9-cfcbb32cf963)

![image](https://github.com/microsoft/terminal/assets/18356694/0a0f4a0e-3ba5-4b61-8f80-1b988fbbb319)

closes microsoft#16577
closes microsoft#16578

src/cascadia/TerminalSettingsModel/ActionMap.cpp

@@ -6,6 +6,7 @@
 #include "ActionMap.h"
 #include "Command.h"
 #include "AllShortcutActions.h"
+#include <LibraryResources.h>
 
 #include "ActionMap.g.cpp"
 
@@ -964,17 +965,32 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
             cmdImpl.copy_from(winrt::get_self<implementation::Command>(command));
 
             const auto inArgs{ command.ActionAndArgs().Args().try_as<Model::SendInputArgs>() };
-
+            const auto inputString{ inArgs ? inArgs.Input() : L"" };
             auto args = winrt::make_self<SendInputArgs>(
                 winrt::hstring{ fmt::format(FMT_COMPILE(L"{:\x7f^{}}{}"),
                                             L"",
                                             numBackspaces,
-                                            (std::wstring_view)(inArgs ? inArgs.Input() : L"")) });
+                                            inputString) });
             Model::ActionAndArgs actionAndArgs{ ShortcutAction::SendInput, *args };
 
             auto copy = cmdImpl->Copy();
             copy->ActionAndArgs(actionAndArgs);
 
+            if (!copy->HasName())
+            {
+                // Here, we want to manually generate a send input name, but
+                // without visualizing space and backspace
+                //
+                // This is exactly the body of SendInputArgs::GenerateName, but
+                // with visualize_nonspace_control_codes instead of
+                // visualize_control_codes, to make filtering in the suggestions
+                // UI easier.
+
+                const auto escapedInput = til::visualize_nonspace_control_codes(std::wstring{ inputString });
+                const auto name = fmt::format(std::wstring_view(RS_(L"SendInputCommandKey")), escapedInput);
+                copy->Name(winrt::hstring{ name });
+            }
+
             return *copy;
         };
 

src/inc/til/string.h

@@ -24,6 +24,24 @@ namespace til // Terminal Implementation Library. Also: "Today I Learned"
         }
         return str;
     }
+    // The same as the above, but it doesn't visualize BS nor SPC.
+    _TIL_INLINEPREFIX std::wstring visualize_nonspace_control_codes(std::wstring str) noexcept
+    {
+        for (auto& ch : str)
+        {
+            // NOT backspace!
+            if (ch < 0x20 && ch != 0x08)
+            {
+                ch += 0x2400;
+            }
+            // NOT space
+            else if (ch == 0x7f)
+            {
+                ch = 0x2421; // replace del with ␡
+            }
+        }
+        return str;
+    }
 
     _TIL_INLINEPREFIX std::wstring visualize_control_codes(std::wstring_view str)
     {