✨ Allow setting local_fs_map even when using UI_UnixDomainServer

[marianosimone]

Description

This is a fix for #741

Basically, allow users to specify the local_fs_map even when using UI_UnixDomainServer. The idea is to maintain the existing behavior when the configuration is not specified, but use it when it is.

From the original context:

Stripe runs ruby on a remote server and VS Code on a laptop. We proxy the unix domain socket from server to laptop, and need to use the fs map feature to translate file paths.

[marianosimone]

@ko1 there's a failing test, but I'm not sure it's related to my changes, as the same test failed in all my other PRs 😕

[ko1]

===============================================================================
Failure: test_default_case(DEBUGGER__::Fork_fork_0):
  Test::Unit::AssertionFailedError: 
  --------------------
  | Debugger Session |
  --------------------
  
  > [1, 10] in /tmp/debug-20220916-1804-xhwni.rb
  > =>   1| pid = fork do
  >      2|   binding.b do: 'p :child_enter'
  >      3|   a = 1
  >      4|   b = 2
  >      5|   c = 3
  >      6|   binding.b do: 'p :child_leave'
  >      7| end
  >      8| sleep 0.5
  >      9| binding.b do: 'p :parent_enter'
  >     10| a = 1
  > =>#0	<main> at /tmp/debug-20220916-1804-xhwni.rb:1
  > b 5
  > (rdbg) b 5
  > #0  BP - Line  /tmp/debug-20220916-1804-xhwni.rb:5 (line)
  > b 10
  > (rdbg) b 10
  > #1  BP - Line  /tmp/debug-20220916-1804-xhwni.rb:10 (line)
  > (rdbg) c
  > DEBUGGER: Attaching after process 37[27](https://github.com/ruby/debug/actions/runs/2973698355/jobs/4951402957#step:4:28) fork to child process 37[36](https://github.com/ruby/debug/actions/runs/2973698355/jobs/4951402957#step:4:37)
  > [4, 13] in /tmp/debug-20220916-1804-xhwni.rb
  >      4|   b = 2
  >      5|   c = 3
  >      6|   binding.b do: 'p :child_leave'
  >      7| end
  >      8| sleep 0.5
  > =>   9| binding.b do: 'p :parent_enter'
  >     10| a = 1
  >     11| b = 2
  >     12| c = 3
  >     13| binding.b do: 'p :parent_leave'
  > =>#0	<main> at /tmp/debug-20220916-1804-xhwni.rb:9
  > (rdbg:binding.break) p :parent_enter
  > => :parent_enter
  > [5, 14] in /tmp/debug-20220916-1804-xhwni.rb
  >      5|   c = 3
  >      6|   binding.b do: 'p :child_leave'
  >      7| end
  >      8| sleep 0.5
  >      9| binding.b do: 'p :parent_enter'
  > =>  10| a = 1
  >     11| b = 2
  >     12| c = 3
  >     13| binding.b do: 'p :parent_leave'
  >     14| Process.waitpid pid
  > =>#0	<main> at /tmp/debug-20220916-1804-xhwni.rb:10
  > 
  > Stop by #1  BP - Line  /tmp/debug-20220916-1804-xhwni.rb:10 (line)
  
  
  
  
  -------------------
  | Failure Message |
  -------------------
  
  Expected the debugger program to finish on LOCAL mode.
/home/runner/work/debug/debug/test/support/assertions.rb:97:in `assert_block'
/home/runner/work/debug/debug/test/support/console_test_case.rb:107:in `rescue in block (2 levels) in debug_code'
/home/runner/work/debug/debug/test/support/console_test_case.rb:92:in `block (2 levels) in debug_code'
/home/runner/work/debug/debug/test/support/console_test_case.rb:209:in `prepare_test_environment'
/home/runner/work/debug/debug/test/support/console_test_case.rb:90:in `block in debug_code'
/home/runner/.rubies/ruby-debug/lib/ruby/3.2.0+2/timeout.rb:188:in `block in timeout'
/home/runner/.rubies/ruby-debug/lib/ruby/3.2.0+2/timeout.rb:36:in `block in catch'
/home/runner/.rubies/ruby-debug/lib/ruby/3.2.0+2/timeout.rb:36:in `catch'
/home/runner/.rubies/ruby-debug/lib/ruby/3.2.0+2/timeout.rb:36:in `catch'
/home/runner/.rubies/ruby-debug/lib/ruby/3.2.0+2/timeout.rb:197:in `timeout'
/home/runner/work/debug/debug/test/support/console_test_case.rb:89:in `debug_code'
/home/runner/work/debug/debug/test/console/config_fork_test.rb:51:in `test_default_case'
     [48](https://github.com/ruby/debug/actions/runs/2973698355/jobs/4951402957#step:4:49): 
     [49](https://github.com/ruby/debug/actions/runs/2973698355/jobs/4951402957#step:4:50):   module ForkTestTemplate
     [50](https://github.com/ruby/debug/actions/runs/2973698355/jobs/4951402957#step:4:51):     def test_default_case
  => [51](https://github.com/ruby/debug/actions/runs/2973698355/jobs/4951402957#step:4:52):       debug_code(program) do
     [52](https://github.com/ruby/debug/actions/runs/2973698355/jobs/4951402957#step:4:53):         # type 'config fork_mode = both' # default
     [53](https://github.com/ruby/debug/actions/runs/2973698355/jobs/4951402957#step:4:54):         type 'b 5'
     [54](https://github.com/ruby/debug/actions/runs/2973698355/jobs/4951402957#step:4:55):         type 'b 10'
===============================================================================

It seems to stick at fork example. Let me check...