Setup initial compiler driver and basic mlir boilerplate

[edg-l]

• Added concrete_session, which holds information about the current compile unit and used by the driver and codegen.
• Added the initial compiler driver, which drives the compilation process using the parser, mlir codegen and linker to produce a binary.

The cli interface or the driver is by no means anything ready but it's enough to be able to compile programs and help the development further.

Like rust, we use a folder to store intermediate files and artifacts (like object files) (like a target/), for now i called it build_artifacts.

cargo r -- --library examples/fib.con produces right now an empty shared library (since we dont have codegen implemented yet)

outputs this:

2024-01-08T15:11:42.387329Z DEBUG concrete_driver: source code:
mod FactorialModule {
    pub fn factorial(x: u64) -> u64  {
        return match x {
            0 -> return 1,
            n -> return n * factorial(n-1),
        };
    }
}

2024-01-08T15:11:42.387409Z DEBUG concrete_driver: Output file: "/snip/concrete/build_artifacts/fib.con"
2024-01-08T15:11:42.387414Z DEBUG concrete_driver: Compiling with session: Session {
    file_path: "examples/fib.con",
    debug_info: Full,
    optlevel: None,
    source: "mod FactorialModule {\n    pub fn factorial(x: u64) -> u64  {\n        return match x {\n            0 -> return 1,\n            n -> return n * factorial(n-1),\n        };\n    }\n}\n",
    library: true,
    target_dir: "/snip/concrete/build_artifacts/",
    output_file: "/snip/concrete/build_artifacts/fib.so",
}
2024-01-08T15:11:42.390431Z DEBUG concrete_codegen_mlir: Compiling to object file
2024-01-08T15:11:42.390443Z DEBUG concrete_codegen_mlir: Target file: "fib.o"
2024-01-08T15:11:42.390501Z DEBUG concrete_codegen_mlir: initialized llvm targets
2024-01-08T15:11:42.390632Z DEBUG concrete_codegen_mlir: filename to llvm: "/snip/concrete/build_artifacts/fib.o"
2024-01-08T15:11:42.397798Z DEBUG concrete_driver: Done in 11.054603ms

[codecov-commenter]

Codecov Report

Attention: 285 lines in your changes are missing coverage. Please review.

Comparison is base (6583301) 52.38% compared to head (a173826) 17.22%.

Files	Patch %	Lines
crates/concrete_codegen_mlir/src/lib.rs	0.00%	108 Missing :warning:
crates/concrete_driver/src/lib.rs	0.00%	43 Missing :warning:
crates/concrete_parser/src/lib.rs	0.00%	41 Missing :warning:
crates/concrete_codegen_mlir/src/context.rs	0.00%	35 Missing :warning:
crates/concrete_codegen_mlir/src/codegen.rs	0.00%	17 Missing :warning:
crates/concrete_codegen_mlir/src/pass_manager.rs	0.00%	13 Missing :warning:
crates/concrete_codegen_mlir/src/module.rs	0.00%	11 Missing :warning:
crates/concrete_session/src/lib.rs	0.00%	7 Missing :warning:
crates/concrete_codegen_mlir/src/error.rs	0.00%	4 Missing :warning:
crates/concrete/src/main.rs	0.00%	2 Missing :warning:
... and 2 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #60 +/- ## =========================================== - Coverage 52.38% 17.22% -35.16% =========================================== Files 14 25 +11 Lines 126 389 +263 =========================================== + Hits 66 67 +1 - Misses 60 322 +262 ```

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:loudspeaker: Have feedback on the report? Share it here.

[unbalancedparentheses]

I will merge it, it looks fine, there are quite a few todo. I think it's a good idea to create issues rather than to keep the todos in the codebase. In a few weeks I will ask to move all the todos to issues.

I was speaking with @igaray. I would have gone the C generation route like Austral is doing. I think it's easier but you guys are proficient with MLIR so let's start with it. If things go sour we can go back, remove the MLIR and start with C generation and we add the MLIR generation afterwards.