Implement recursively & wildcard functionality for nob_read_entire_dir()

[gaogao-qwq]

Basically just a GNU Make wildcard() function.

e.g. For folders with the following hierarchy (which is a common case for C/C++ developers nowadays, sigh).

.
├── external
│   ├── foobar
│   │   ├── foobar.h
│   │   ├── libfoobar.a
│   │   └── libfoobar.so
│   └── foobarbaz
│       ├── foobarbaz.h
│       ├── libfoobarbaz.a
│       └── libfoobarbaz.so
├── include
│   ├── bar
│   │   └── bar.h
│   ├── baz.h
│   └── foo
│       └── foo.h
└── src
    ├── bar
    │   └── bar.c
    ├── baz.c
    └── foo
        └── foo.c

Running read_entire_dir(".", &children) will give u a list of

.
..
src
external
include

Running read_entire_dir(".", &children, .recursively = true) will give u a list of

src/bar/bar.c
src/baz.c
src/foo/foo.c
external/foobarbaz/libfoobarbaz.a
external/foobarbaz/libfoobarbaz.so
external/foobarbaz/foobarbaz.h
external/foobar/libfoobar.a
external/foobar/foobar.h
external/foobar/libfoobar.so
include/bar/bar.h
include/baz.h
include/foo/foo.h

Running read_entire_dir(".", &dlls, .wildcard = "external/**/*.so" will give u a list of

external/foobarbaz/libfoobarbaz.so
external/foobar/libfoobar.so

[rexim]

These functions give me the same vibe as nob_cmd_run_sync_redirect_and_reset. Maybe .recursively and .wildcard should be optional parameters like in nob_cmd_run()?