Fixed undefined $search_base

[snipe]

This should hopefully fix #13961, where if a user didn't pass the script a location ID or a base DN, it would crash with an undefined $search_base error.

@uberbrady can you take a look and test with our LDAP server? I don't have my LDAP test rig up right now.

[what-the-diff]

PR Summary

• Inclusion of New Variable
  An additional variable named $search_base has been introduced. This gathers value from the specific setting related to the LDAP base DN (Directory Name).

• Manual Base DN Specification
  A new conditional statement has been incorporated. This provides the ability for a user to manually specify a base DN. This adds flexibility to the system, accommodating situations where automatic DN retrieval may not be appropriate or efficient.

• Filter Specification
  Another conditional statement has been introduced which grants users the provision of specifying a filter. This move brings in better customization and refined search capabilities to the users.

• Exception Handling Enhancement
  We've increased the robustness of our software by incorporating a try-catch block. This will effectively handle exceptions, ensuring that instead of causing a software crash, these incidents will now return a user-friendly error message. This will greatly improve the user experience and overall reliability of our system.

[uberbrady]

This works, the logic is sound - it all seems like it's doing the right stuff. I can confirm that without the change, my LDAP syncs would give that same error message. And with this change, I instead get the correct behavior.

The only 'real' problem was that the $search_base variable was falling out of scope, so hoisting it up (as we did here) would've been enough to fix it (the null case of the search_base parameter will just pull in the settings' search_base, so that would've been enough).

So I think just in the process of tweaks here and there and refactors and whatnot we must've somehow knocked this one off-kilter. Whoopsie :(

Thank you for the fix and let's get this hot!