[lldb] Add builtin e alias for expression (llvm#115359)

The changes in 461f859 (llvm#65974) resulted in a change
in behavior not just for completion, but also for selection of inexect
commands.

Since many use `e` to mean `expression`, this change adds an alias for
`e`. Note that the referenced change similarly aliases `h` to `help`.

Author: kastiglione

lldb/source/Interpreter/CommandInterpreter.cpp

@@ -441,6 +441,8 @@ void CommandInterpreter::Initialize() {
 
   cmd_obj_sp = GetCommandSPExact("expression");
   if (cmd_obj_sp) {
+    // Ensure `e` runs `expression`.
+    AddAlias("e", cmd_obj_sp);
     AddAlias("call", cmd_obj_sp, "--")->SetHelpLong("");
     CommandAlias *parray_alias =
         AddAlias("parray", cmd_obj_sp, "--element-count %1 --");

lldb/test/API/functionalities/abbreviation/TestAbbreviations.py

@@ -20,6 +20,10 @@ def test_command_abbreviations_and_aliases(self):
         self.assertTrue(result.Succeeded())
         self.assertEqual("apropos script", result.GetOutput())
 
+        command_interpreter.ResolveCommand("e", result)
+        self.assertTrue(result.Succeeded())
+        self.assertEqual("expression", result.GetOutput())
+
         command_interpreter.ResolveCommand("h", result)
         self.assertTrue(result.Succeeded())
         self.assertEqual("help", result.GetOutput())