Wrap handling during `ninja reconfigure` ignores project subproject_dir setting

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**Describe the bug**

During project regeneration, when Meson fires dependency fallback handling and finds wrap redirect .wrap's, it fails when a project is using subproject_dir due to this process ignoring that project option.

**To Reproduce**
`meson.build:`
```meson
project('proj', 'cpp', subproject_dir: 'deps')
subproj = dependency('subproj', fallback: ['subproj', 'subproj_dep'])
executable('proj', 'test.cxx', dependencies: [subproj], native: true)
```

`test.cxx`:
```c++
int main(int, char **) { return 0; }
```

`deps/subproj/meson.build`:
```meson
project('subproj', 'cpp')
substrate = dependency('substrate', fallback: ['substrate', 'substrate_dep'])
lib = library('subproj', 'test.cxx', dependencies: [substrate])
subproj_dep = declare_dependency(link_with: lib)
```

`touch deps/subproj/test.cxx`

`deps/subproj/subprojects/substrate.wrap`:
```wrap
[wrap-git]
url = https://github.com/bad-alloc-heavy-industries/substrate.git
revision = head
clone-recursive = false
```

Then run `meson build --force-fallback-for substrate` (this will be fine and work), `cd build`, and `ninja reconfigure`. The result will be the error

`../meson.build:1:0: ERROR: wrap-redirect filename must be in the form foo/subprojects/bar.wrap`

**Expected behavior**

Project cleanly reconfigures without error

**system parameters**
* Native build
* Any OS (test case is written for Linux)
* Python 3.9.5
* Meson 0.58.1
* Ninja 1.10.2

Reproduce the failure with the shown meson.build files, deps/subproj/meson.build, and deps/subproj/subprojects/substrate.wrap by running meson build --force-fallback-for substrate followed by ninja reconfigure. Start at the wrap redirect handling during regeneration and trace how subproject_dir is resolved. Done means the project reconfigures cleanly with subproject_dir: 'deps'.

Written by the indexing model from the issue text.