Reorganise integration tests

[Xenira]

We currently have one big lib.rs, which is getting bigger with each test case.

This should be split to have only the relevant test cases for each php test file.

[Norbytus]

I think about test, maybe we can try use same way as in php-src? They have phpt.
And organize integration test like this

cases/mod.rs
cases/{scope_name}/*.rs
lib.rs

[Xenira]

Yeah, was thinking about something like this:

└── tests/
    ├── src/
    │   ├── lib.rs
    │   └── integration/
    │       ├── mod.rs
    │       ├── array/
    │       │   ├── mod.rs
    │       │   ├── array.rs
    │       │   └── array.php
    │       ├── binary/
    │       │   ├── mod.rs
    │       │   ├── binary.rs
    │       │   └── binary.php
    │       └── ...
    └── Cargo.toml