Fix bug when restarting binary after set disable-randomization off

There is a bug when the `pwndbg.auxv.get()` and `pwndbg.vmmap.get()` caches are not resetted when the binary is restarted. This causes an error when `disable-randomization` is set to off and the binary is restarted.

TL;DR to reproduce:
1. Run `gdb /bin/ls`
2. Invoke `entry`
3. Invoke `set disable-randomization off`
4. Invoke `starti` or `entry`

Or it can be seen here:
```
dc@dc:~$ gdb /bin/ls -q
pwndbg: loaded 195 commands. Type pwndbg [filter] for a list.
pwndbg: created $rebase, $ida gdb functions (can be used with print/break)
Reading symbols from /bin/ls...
(No debugging symbols found in /bin/ls)
pwndbg> set context-sections ''
Sections set to be empty. FYI valid values are: regs, disasm, args, code, stack, backtrace, expressions, ghidra
Set which context sections are displayed (controls order) to ''
pwndbg> entry
Temporary breakpoint 1 at 0x55555555a810
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Temporary breakpoint 1, 0x000055555555a810 in ?? ()
pwndbg> set exception-verbose on
Set whether to print a full stacktrace for exceptions raised in Pwndbg commands to True
pwndbg> set disable-randomization off
pwndbg> starti
Starting program: /usr/bin/ls
Traceback (most recent call last):
  File "/home/dc/src/pwndbg/pwndbg/events.py", line 165, in caller
    func()
  File "/home/dc/src/pwndbg/pwndbg/memoize.py", line 194, in __reset_on_base
    base = pwndbg.elf.exe().address if pwndbg.elf.exe() else None
  File "/home/dc/src/pwndbg/pwndbg/proc.py", line 71, in wrapper
    return func(*a, **kw)
  File "/home/dc/src/pwndbg/pwndbg/memoize.py", line 46, in __call__
    value = self.func(*args, **kwargs)
  File "/home/dc/src/pwndbg/pwndbg/elf.py", line 182, in exe
    return load(e)
  File "/home/dc/src/pwndbg/pwndbg/elf.py", line 220, in load
    return get_ehdr(pointer)[1]
  File "/home/dc/src/pwndbg/pwndbg/elf.py", line 241, in get_ehdr
    if pwndbg.memory.read(vmmap.start, 4) == b'\x7fELF':
  File "/home/dc/src/pwndbg/pwndbg/memory.py", line 40, in read
    result = gdb.selected_inferior().read_memory(addr, count)
gdb.MemoryError: Cannot access memory at address 0x555555558000
```

This commit fixes the above problem by making sure those function caches are cleared on binary start.

pwndbg/auxv.py

@@ -102,6 +102,7 @@ class AUXV(dict):
         return str({k:v for k,v in self.items() if v is not None})
 
 @pwndbg.memoize.reset_on_objfile
+@pwndbg.memoize.reset_on_start
 def get():
     return use_info_auxv() or walk_stack() or AUXV()
 

pwndbg/vmmap.py

@@ -33,6 +33,7 @@ explored_pages = []
 # List of custom pages that can be managed manually by vmmap_* commands family
 custom_pages = []
 
+@pwndbg.memoize.reset_on_start
 @pwndbg.memoize.reset_on_stop
 def get():
     if not pwndbg.proc.alive:
@@ -142,6 +143,7 @@ def clear_custom_page():
     pwndbg.memoize.reset()
 
 
+@pwndbg.memoize.reset_on_start
 @pwndbg.memoize.reset_on_stop
 def proc_pid_maps():
     """