Fix spelling mistakes across the whole repository (#3808)

**Update:** Pushed additional changes based on the review comments.

**This pull request fixes various spelling mistakes in this
repository.**

Most of the changes are contained in the first **3** commits:

- `Fix spelling mistakes in comments and docs`

- `Fix spelling mistakes in test names`

- `Fix spelling mistakes in error messages, panic messages, logs and
tracing`

Other source code spelling mistakes are separated into individual
commits for easier reviewing:

- `Fix the spelling of 'authority'`

- `Fix the spelling of 'REASONABLE_HEADERS_IN_JUSTIFICATION_ANCESTRY'`

- `Fix the spelling of 'prev_enqueud_messages'`

- `Fix the spelling of 'endpoint'`

- `Fix the spelling of 'children'`

- `Fix the spelling of 'PenpalSiblingSovereignAccount'`

- `Fix the spelling of 'PenpalSudoAccount'`

- `Fix the spelling of 'insufficient'`

- `Fix the spelling of 'PalletXcmExtrinsicsBenchmark'`

- `Fix the spelling of 'subtracted'`

- `Fix the spelling of 'CandidatePendingAvailability'`

- `Fix the spelling of 'exclusive'`

- `Fix the spelling of 'until'`

- `Fix the spelling of 'discriminator'`

- `Fix the spelling of 'nonexistent'`

- `Fix the spelling of 'subsystem'`

- `Fix the spelling of 'indices'`

- `Fix the spelling of 'committed'`

- `Fix the spelling of 'topology'`

- `Fix the spelling of 'response'`

- `Fix the spelling of 'beneficiary'`

- `Fix the spelling of 'formatted'`

- `Fix the spelling of 'UNKNOWN_PROOF_REQUEST'`

- `Fix the spelling of 'succeeded'`

- `Fix the spelling of 'reopened'`

- `Fix the spelling of 'proposer'`

- `Fix the spelling of 'InstantiationNonce'`

- `Fix the spelling of 'depositor'`

- `Fix the spelling of 'expiration'`

- `Fix the spelling of 'phantom'`

- `Fix the spelling of 'AggregatedKeyValue'`

- `Fix the spelling of 'randomness'`

- `Fix the spelling of 'defendant'`

- `Fix the spelling of 'AquaticMammal'`

- `Fix the spelling of 'transactions'`

- `Fix the spelling of 'PassingTracingSubscriber'`

- `Fix the spelling of 'TxSignaturePayload'`

- `Fix the spelling of 'versioning'`

- `Fix the spelling of 'descendant'`

- `Fix the spelling of 'overridden'`

- `Fix the spelling of 'network'`

Let me know if this structure is adequate.

**Note:** The usage of the words `Merkle`, `Merkelize`, `Merklization`,
`Merkelization`, `Merkleization`, is somewhat inconsistent but I left it
as it is.

~~**Note:** In some places the term `Receival` is used to refer to
message reception, IMO `Reception` is the correct word here, but I left
it as it is.~~

~~**Note:** In some places the term `Overlayed` is used instead of the
more acceptable version `Overlaid` but I also left it as it is.~~

~~**Note:** In some places the term `Applyable` is used instead of the
correct version `Applicable` but I also left it as it is.~~

**Note:** Some usage of British vs American english e.g. `judgement` vs
`judgment`, `initialise` vs `initialize`, `optimise` vs `optimize` etc.
are both present in different places, but I suppose that's
understandable given the number of contributors.

~~**Note:** There is a spelling mistake in `.github/CODEOWNERS` but it
triggers errors in CI when I make changes to it, so I left it as it
is.~~

substrate/frame/balances/src/tests/currency_tests.rs

@@ -1024,7 +1024,7 @@ fn slash_consumed_slash_partial_works() {
 }
 
 #[test]
-fn slash_on_non_existant_works() {
+fn slash_on_non_existent_works() {
 	ExtBuilder::default().existential_deposit(100).build_and_execute_with(|| {
 		// Slash on non-existent account is okay.
 		assert_eq!(Balances::slash(&12345, 1_300), (NegativeImbalance::new(0), 1300));
@@ -1071,7 +1071,7 @@ fn slash_reserved_overslash_does_not_touch_free_balance() {
 }
 
 #[test]
-fn slash_reserved_on_non_existant_works() {
+fn slash_reserved_on_non_existent_works() {
 	ExtBuilder::default().existential_deposit(100).build_and_execute_with(|| {
 		// Slash on non-existent account is okay.
 		assert_eq!(Balances::slash_reserved(&12345, 1_300), (NegativeImbalance::new(0), 1300));

substrate/frame/balances/src/tests/reentrancy_tests.rs

@@ -44,7 +44,7 @@ fn transfer_dust_removal_tst1_should_work() {
 			assert_eq!(Balances::free_balance(&2), 0);
 
 			// As expected beneficiary account 3
-			// received the transfered fund.
+			// received the transferred fund.
 			assert_eq!(Balances::free_balance(&3), 450);
 
 			// Dust balance is deposited to account 1
@@ -123,7 +123,7 @@ fn repatriating_reserved_balance_dust_removal_should_work() {
 
 			// Reserve a value on account 2,
 			// Such that free balance is lower than
-			// Exestintial deposit.
+			// Existential deposit.
 			assert_ok!(Balances::transfer_allow_death(RuntimeOrigin::signed(2), 1, 450));
 
 			// Since free balance of account 2 is lower than