authorizer builder

[Geal]

Fix #194, #193, #192

This adds an AuthorizerBuilder struct that is used to create an Authorizer. All of the mutable behaviour, like adding facts or executing Datalog rules is moved into the builder, while the authorizer is limited to read-only queries (still requiring self mutability to track execution time). The AuthorizerBuilder is compatible with snapshots, to store and reuse checks and policies. It has a build method taking a token as argument, and a build_unauthenticated for authorization without token.

The builder APIs are alo changing. Before, we had the following:

 let mut builder = Biscuit::builder();	
builder.add_fact(r"right("file1", "read")"#)?;
builder.add_fact(r"right("file2", "read")"#)?;
let token = builder.build()?;

Builders are now constructed like this:

let token = Biscuit::builder()
    .fact(r"right("file1", "read")"#)?
    .fact(r"right("file2", "read")"#)?
    .build()?;

[codspeed-hq]

CodSpeed Performance Report

Merging #250 will degrade performances by 10.44%

_{Comparing geal/authorizer-builder (aaaa9fd) with v5 (6d55705)}

Summary

❌ 1 (👁 1) regressions
✅ 11 untouched benchmarks

Benchmarks breakdown

	Benchmark	v5	geal/authorizer-builder	Change
👁	checks_block_create_verifier2	59.5 µs	66.4 µs	-10.44%

[Geal]

the performance regression is due to AuthorizerBuilder::build executing Datalog rules before returning the authorizer, while the original benchmark was only testing the creation of an authorizer from a token, so it translates the block but does not execute rules