Evaluate arguments passed to vmmap (#1085)

## Description

Attempts to parse and eval an argument passed to `vmmap`.

This makes `vmmap $rip`, for example, work.

This is useful as it is easier to look up the memory section a pointer
contained in a register/variable points to. It's also more consistent
with commands like `dereference`

docs/commands/vmmap.md

@@ -15,3 +15,7 @@ determine which section it belongs to.
 ![vmmap-grep](https://i.imgur.com/ZFF4QVf.png)
 
 ![vmmap-address](https://i.imgur.com/hfcs1jH.png)
+
+The address can be also be given in the form of a register or variable.
+
+![vmmap-register](https://i.imgur.com/RlZA6NU.png)

gef.py

@@ -8711,6 +8711,10 @@ def do_invoke(self, argv: List[str]) -> None:
                 addr = int(argv[0], 0)
                 if addr >= entry.page_start and addr < entry.page_end:
                     self.print_entry(entry)
+            else:
+                addr = safe_parse_and_eval(argv[0])
+                if addr is not None and addr >= entry.page_start and addr < entry.page_end:
+                    self.print_entry(entry)
         return
 
     def print_entry(self, entry: Section) -> None:

tests/commands/vmmap.py

@@ -21,3 +21,6 @@ def test_cmd_vmmap(self):
 
         res = gdb.execute("vmmap stack", to_string=True)
         self.assertGreater(len(res.splitlines()), 1)
+
+        res = gdb.execute("vmmap $rip", to_string=True)
+        self.assertEqual(len(res.splitlines()), 2)