Replace libsecp256k1 with secp256k1 (#10798)

* Replace libsecp256k1 with secp256k1

* Wipe ecdsa secret key from memory on drop

* Some comments for a known issue

* Safer core crypto primitives `from_slice` constructor

Previous version panics if slice lenght is not the expected one.

* Unit test fix

* Enable use of global secp256k1 context

* Better comments for ecdsa `Pair` drop

* Replace `libsecp256k1` with `seco256k1` in `beefy-mmr`

Used to convert ecdsa public key to ETH address

* Replace `libsecp256k1` with `secp256k1` in FRAME `contracts`benchmarks

* Temporary rollback of `beefy-mmr` to libsecp256k1

Check for detected build issues

* Cargo fmt

* Rollback of FRAME `contracts` benchmarks to `libsecp256k1`

* Rollback for unrelated changes

* Typo fix

* Add comments for deprecated `ecdsa_verify` and `secp256k1_ecdsa_recover`

substrate/Cargo.lock

@@ -8382,7 +8382,6 @@ version = "0.10.0-dev"
 dependencies = [
  "hex-literal",
  "lazy_static",
- "libsecp256k1",
  "lru 0.6.6",
  "parity-scale-codec",
  "parking_lot 0.12.0",
@@ -9170,6 +9169,25 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "secp256k1"
+version = "0.21.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ab7883017d5b21f011ef8040ea9c6c7ac90834c0df26a69e4c0b06276151f125"
+dependencies = [
+ "rand 0.6.5",
+ "secp256k1-sys",
+]
+
+[[package]]
+name = "secp256k1-sys"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "957da2573cde917463ece3570eab4a0b3f19de6f1646cde62e6fd3868f566036"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "secrecy"
 version = "0.8.0"
@@ -9817,6 +9835,7 @@ dependencies = [
  "regex",
  "scale-info",
  "schnorrkel",
+ "secp256k1",
  "secrecy",
  "serde",
  "serde_json",
@@ -9927,6 +9946,7 @@ dependencies = [
  "log 0.4.14",
  "parity-scale-codec",
  "parking_lot 0.12.0",
+ "secp256k1",
  "sp-core",
  "sp-externalities",
  "sp-keystore",