Respect submodules in aqua-registry repository

[iilyak]

Since mise doesn't support merging of two registries yet. I tried to simulate it using git submodules.

❯ tree
.
├── .gitmodules
├── aqua-registry
└── pkgs
    ├── public@ -> ../aqua-registry/pkgs
    └── iilyak
        ├── lua
        │   └── lua
        │       └── registry.yaml
        └── spotbugs
            └── spotbugs
                └── registry.yaml

❯ cat .gitmodules
[submodule "aqua-registry"]
	path = aqua-registry
	url = https://github.com/aquaproj/aqua-registry.git

However git2 in mise doesn't initialize the submodule when it checks out the aqua registry which causes the aqua-registry folder to be empty. As a result I cannot install packages defined in public aqua registry.

Here is the structure of the checkout repository

❯ tree /Users/iilyak/Library/Caches/mise/aqua-registry
/Users/iilyak/Library/Caches/mise/aqua-registry
├── pkgs
│   ├── cloudant
│   │   ├── lua
│   │   │   └── lua
│   │   │       └── registry.yaml
│   │   └── spotbugs
│   │       └── spotbugs
│   │           └── registry.yaml
│   └── public
└── aqua-registry

❯ ls -la /Users/iilyak/Library/Caches/mise/aqua-registry
total 8
drwxr-xr-x   6 iilyak  staff  192 Jan 22 21:19 ./
drwxr-xr-x  31 iilyak  staff  992 Jan 23 13:52 ../
drwxr-xr-x  12 iilyak  staff  384 Jan 22 21:19 .git/
-rw-r--r--   1 iilyak  staff  103 Jan 22 21:19 .gitmodules
drwxr-xr-x   2 iilyak  staff   64 Jan 22 21:19 aqua-registry/
drwxr-xr-x   4 iilyak  staff  128 Jan 22 21:19 pkgs/

❯ ls -la /Users/iilyak/Library/Caches/mise/aqua-registry/aqua-registry/
total 0
drwxr-xr-x  2 iilyak  staff   64 Jan 22 21:19 ./
drwxr-xr-x  6 iilyak  staff  192 Jan 22 21:19 ../