Unify Stark and Secp256 Curves interfaces (#1352)

<!-- Reference any GitHub issues resolved by this PR -->

Closes #1214 
Closes #1257 
Closes #1259

## Introduced changes

<!-- A brief description of the changes -->

- removed `signature/interface.cairo`
- added `signature/stark_curve.cairo`,
`signature/secp256k1_curve.cairo`, `signature/secp256r1_curve.cairo`
- `KeyPair` now requires the type of secret and public key passed

```rust
// Stark Curve
let key_pair = KeyPairTrait::<felt252, felt252>::generate();

// Secp256k1 Curve
let key_pair = KeyPairTrait::<u256, Secp256k1Point>::generate();

// Secp256r1 Curve
let key_pair = KeyPairTrait::<u256, Secp256r1Point>::generate();
```

## Checklist

<!-- Make sure all of these are complete -->

- [x] Linked relevant issue
- [x] Updated relevant documentation - #1259 
- [x] Added relevant tests
- [x] Performed self-review of the code
- [x] Added changes to `CHANGELOG.md`

Author: drknzz

CHANGELOG.md

@@ -9,11 +9,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Forge
 
+#### Added
+
+- `Secp256k1` and `Secp256r1` curves support for `KeyPair` in `snforge_std`
+
 #### Changed
 
 - maximum number of computational steps per call set to current Starknet limit (3M)
 - `mean` and `std deviation` fields are displayed for gas usage while running fuzzing tests 
 - Cairo edition in `snforge_std` and `sncast_std` set to `2023_10`
+- `snforge_std::signature` module with `stark_curve`, `secp256k1_curve` and `secp256r1_curve` submodules
 
 #### Fixed
 

Cargo.lock

@@ -34,6 +34,8 @@ fs2 = "0.4.3"
 flate2 = "1.0.27"
 scarb-api = { path = "../scarb-api" }
 runtime = { path = "../runtime" }
+k256 = { version = "0.13.2", features = ["sha256", "ecdsa", "serde"] }
+p256 = { version = "0.13.2", features = ["sha256", "ecdsa", "serde"] }
 sierra-casm = { path = "../sierra-casm" }
 
 [dev-dependencies]