Ensure DNS command config loading does not crash msfconsole

[adfoster-r7]

Closes #18756
Continuation of #18662

When starting termux (which isn't supported) msfconsole crashes due to failing to load /etc/resolv.conf:

However this could theoretically happen on other OS versions too so I've put in a naive rescue for now

Notes:

• This functionality should be behind a feature flag still
• We shouldn't crash
• For termux we should be reading a different file location: /data/data/com.termux/files/usr/etc/resolv.conf
• We probably want better fallback behavior, should we use cloudflare DNS or similar in the error scenario?

Verification

List the steps needed to make sure this thing works

• Ensure termux no longer crashes on bootup
• Ensure that a missing config file no longer crashes msfconsole on bootup, I changed this config manually:

      Defaults = {
        :config_file => "/etc/resolv.conf",

[dwelch-r7]

Changes seem good to me, working locally after changing the default config

Before:

$ ./msfconsole                                                                                                                                                                                                                                ‹ruby-3.0.5@metasploit-framework›
Metasploit tip: Search can apply complex filters such as search cve:2009
type:exploit, see all the filters with help search
/Users/dwelch/dev/metasploit-framework/lib/net/dns/resolver.rb:1087:in `foreach': No such file or directory @ rb_sysopen - /etc/garbage/resolv.conf (Errno::ENOENT)
	from /Users/dwelch/dev/metasploit-framework/lib/net/dns/resolver.rb:1087:in `parse_config_file'
	from /Users/dwelch/dev/metasploit-framework/lib/rex/proto/dns/resolver.rb:66:in `initialize'
	from /Users/dwelch/dev/metasploit-framework/lib/rex/proto/dns/cached_resolver.rb:25:in `initialize'
	from /Users/dwelch/dev/metasploit-framework/lib/msf/ui/console/driver.rb:83:in `new'
	from /Users/dwelch/dev/metasploit-framework/lib/msf/ui/console/driver.rb:83:in `initialize'
	from /Users/dwelch/dev/metasploit-framework/lib/metasploit/framework/command/console.rb:66:in `new'
	from /Users/dwelch/dev/metasploit-framework/lib/metasploit/framework/command/console.rb:66:in `driver'
	from /Users/dwelch/dev/metasploit-framework/lib/metasploit/framework/command/console.rb:54:in `start'
	from /Users/dwelch/dev/metasploit-framework/lib/metasploit/framework/command/base.rb:82:in `start'
	from ./msfconsole:23:in `<main>'

After:

$ ./msfconsole                                                                                                                                                                                                                                ‹ruby-3.0.5@metasploit-framework›
Metasploit tip: After running db_nmap, be sure to check out the result
of hosts and services


      .:okOOOkdc'           'cdkOOOko:.
    .xOOOOOOOOOOOOc       cOOOOOOOOOOOOx.
   :OOOOOOOOOOOOOOOk,   ,kOOOOOOOOOOOOOOO:
  'OOOOOOOOOkkkkOOOOO: :OOOOOOOOOOOOOOOOOO'
  oOOOOOOOO.    .oOOOOoOOOOl.    ,OOOOOOOOo
  dOOOOOOOO.      .cOOOOOc.      ,OOOOOOOOx
  lOOOOOOOO.         ;d;         ,OOOOOOOOl
  .OOOOOOOO.   .;           ;    ,OOOOOOOO.
   cOOOOOOO.   .OOc.     'oOO.   ,OOOOOOOc
    oOOOOOO.   .OOOO.   :OOOO.   ,OOOOOOo
     lOOOOO.   .OOOO.   :OOOO.   ,OOOOOl
      ;OOOO'   .OOOO.   :OOOO.   ;OOOO;
       .dOOo   .OOOOocccxOOOO.   xOOd.
         ,kOl  .OOOOOOOOOOOOO. .dOk,
           :kk;.OOOOOOOOOOOOO.cOk:
             ;kOOOOOOOOOOOOOOOk:
               ,xOOOOOOOOOOOx,
                 .lOOOOOOOl.
                    ,dOd,
                      .

       =[ metasploit v6.3.54-dev-7ce13101df               ]
+ -- --=[ 2393 exploits - 1235 auxiliary - 421 post       ]
+ -- --=[ 1388 payloads - 46 encoders - 11 nops           ]
+ -- --=[ 9 evasion                                       ]

Metasploit Documentation: https://docs.metasploit.com/

msf6 auxiliary(scanner/smb/smb_enumshares) >

[dwelch-r7]

Release Notes

Fixes an issue where Metasploit fails to start when resolv.conf cannot be found