Independence of Slot-based algorithms from system Timestamp (#12224)

* Remove timestamp from SlotInfo

* Expose as millis instead of secs

* Nits

* Fix test after field removal

* Yet another test fix

* On the fly timestamp computation

* Removed slot timestamp from logs

* Removed reference to timestamp from slots subsystem

* Slot based algorithm tests do not require timstamp inherent anymore

* Remove junk files

* Further tests cleanup

* Trigger pipeline

* Apply code suggestions

* Trigger pipeline

Co-authored-by: André Silva <andrerfosilva@gmail.com>

substrate/primitives/timestamp/src/lib.rs

@@ -56,6 +56,17 @@ impl Timestamp {
 	pub fn checked_sub(self, other: Self) -> Option<Self> {
 		self.0.checked_sub(other.0).map(Self)
 	}
+
+	/// The current timestamp using the system time.
+	#[cfg(feature = "std")]
+	pub fn current() -> Self {
+		use std::time::SystemTime;
+
+		let now = SystemTime::now();
+		now.duration_since(SystemTime::UNIX_EPOCH)
+			.expect("Current time is always after unix epoch; qed")
+			.into()
+	}
 }
 
 impl sp_std::ops::Deref for Timestamp {
@@ -165,18 +176,6 @@ impl TimestampInherentData for InherentData {
 	}
 }
 
-/// The current timestamp using the system time.
-///
-/// This timestamp is the time since the UNIX epoch.
-#[cfg(feature = "std")]
-fn current_timestamp() -> std::time::Duration {
-	use std::time::SystemTime;
-
-	let now = SystemTime::now();
-	now.duration_since(SystemTime::UNIX_EPOCH)
-		.expect("Current time is always after unix epoch; qed")
-}
-
 /// Provide duration since unix epoch in millisecond for timestamp inherent.
 #[cfg(feature = "std")]
 pub struct InherentDataProvider {
@@ -190,7 +189,7 @@ impl InherentDataProvider {
 	pub fn from_system_time() -> Self {
 		Self {
 			max_drift: std::time::Duration::from_secs(60).into(),
-			timestamp: current_timestamp().into(),
+			timestamp: Timestamp::current(),
 		}
 	}