Defer loading all DWOs by default when dumping separate_debug-info (#146166)

### Summary
Currently `target modules dump separate separate-debug-info`
automatically loads up all DWO files, even if deferred loading is
enabled through debug_names. Then, as expected all DWO files (assuming
there is no error loading it), get marked as "loaded".

This change adds the option `--force-load-all-debug-info` or `-f` for
short to force loading all debug_info up, if it hasn't been loaded yet.
Otherwise, it will change default behavior to not load all debug info so
that the correct DWO files will show up for each modules as "loaded" or
not "loaded", which could be helpful in cases where we want to know
which particular DWO files were loaded.

### Testing
#### Unit Tests
Added additional unit tests
`test_dwos_load_json_with_debug_names_default` and
`test_dwos_load_json_with_debug_names_force_load_all` to test both
default behavior and loading with the new flag
`--force-load-all-debug-info`, and changed expected behavior in
`test_dwos_loaded_symbols_on_demand`.
```
bin/lldb-dotest -p TestDumpDwo ~/llvm-project/lldb/test/API/commands/target/dump-separate-debug-info/dwo
```

#### Manual Testing
Compiled a simple binary w/ `--gsplit-dwarf --gpubnames` and loaded it
up:
```
(lldb) target create "./a.out"
Current executable set to '/home/qxy11/hello-world/a.out' (x86_64).
(lldb) help target modules dump separate-debug-info
List the separate debug info symbol files for one or more target modules.

Syntax: target modules dump separate-debug-info <cmd-options> [<filename> [<filename> [...]]]

Command Options Usage:
  target modules dump separate-debug-info [-efj] [<filename> [<filename> [...]]]

       -e ( --errors-only )
            Filter to show only debug info files with errors.

       -f ( --force-load-all-debug-info )
            Load all debug info files.

       -j ( --json )
            Output the details in JSON format.

     This command takes options and free-form arguments.  If your arguments resemble option specifiers (i.e., they start with a - or --), you must use ' -- ' between the end of the
     command options and the beginning of the arguments.
(lldb) target modules dump separate-debug-info --j
[
  {
    "separate-debug-info-files": [
      {  ...
        "dwo_name": "main.dwo",
        "loaded": false
      },
      {  ...
        "dwo_name": "foo.dwo",
        "loaded": false
      },
      { ...
        "dwo_name": "bar.dwo",
        "loaded": false
      }
    ],
  }
]
(lldb) b main
Breakpoint 1: where = a.out`main + 15 at main.cc:3:12, address = 0x00000000000011ff
(lldb) target modules dump separate-debug-info --j
[
  {
    "separate-debug-info-files": [
      { ...
        "dwo_name": "main.dwo",
        "loaded": true,
        "resolved_dwo_path": "/home/qxy11/hello-world/main.dwo"
      },
      { ...
        "dwo_name": "foo.dwo",
        "loaded": false
      },
      { ...
        "dwo_name": "bar.dwo",
        "loaded": false
      }
    ],
  }
]
(lldb) b foo
Breakpoint 2: where = a.out`foo(int) + 11 at foo.cc:12:11, address = 0x000000000000121b
(lldb) target modules dump separate-debug-info --j
[
  {
    "separate-debug-info-files": [
      { ...
        "dwo_name": "main.dwo",
        "loaded": true,
        "resolved_dwo_path": "/home/qxy11/hello-world/main.dwo"
      },
      { ...
        "dwo_name": "foo.dwo",
        "loaded": true,
        "resolved_dwo_path": "/home/qxy11/hello-world/foo.dwo"
      },
      { ...
        "dwo_name": "bar.dwo",
        "loaded": false
      }
    ],
  }
]
(lldb) b bar
Breakpoint 3: where = a.out`bar(int) + 11 at bar.cc:10:9, address = 0x000000000000126b
(lldb) target modules dump separate-debug-info --j
[
  {
    "separate-debug-info-files": [
      { ...
        "dwo_name": "main.dwo",
        "loaded": true,
        "resolved_dwo_path": "/home/qxy11/hello-world/main.dwo"
      },
      { ...
        "dwo_name": "foo.dwo",
        "loaded": true,
        "resolved_dwo_path": "/home/qxy11/hello-world/foo.dwo"
      },
      { ...
        "dwo_name": "bar.dwo",
        "loaded": true,
        "resolved_dwo_path": "/home/qxy11/hello-world/bar.dwo"
      }
    ],
  }
]
```