Batch signature verification (#5023)

* create parallel tasks extension

* make type system happy

* basic externalities

* test for dynamic extensions

* batching test

* remove premature verify_batch

* shnschnorrkel batch

* alter test

* shnschnorrkel test

* executive batching

* some docs

* also multi/any signatgures

* error propagation

* styling

* make verification extension optional

* experimental ed25519 parallelization

* some merge fallout

* utilize task executor

* merge fallout

* utilize task executor more

* another merge fallout

* feature-gate sp-io

* arrange toml

* fix no-std

* sr25519 batching and refactoring

* add docs

* fix name

* add newline

* fix block import test

* long sr25519 test

* blocking instead of parking

* move everything in crypto

* return batch_verify to check :)

* use condvars

* use multi-threaded executor for benches

* don't call via host interface

* try no spawning

* add true

* cleanup

* straighten batching

* remove signature check from this test (?)

* remove now pointless test

* remove another now useless test

* fix warnings

* Revert "remove another now useless test"

This reverts commit bbdec24b.

* rethink the sp-io-part

* Revert "remove now pointless test"

This reverts commit 4d553066

.

* fix wording

* add  wording

* add todo and fix

* return check and fix

* add logging in sp-io

* Update primitives/io/src/batch_verifier.rs

Co-Authored-By: cheme <[email protected]>

* address review and use std condvar

* account for early exit

* address reivew

* address review

* more suggestions

* add docs for batch verification

* remove unused

* more review suggestions

* move to sp-runtime

* add expects

* remove blocks

* use entry

* Update primitives/io/src/batch_verifier.rs

Co-Authored-By: Bastian Köcher <[email protected]>

* Update primitives/externalities/src/extensions.rs

Co-Authored-By: Bastian Köcher <[email protected]>

* update overlooked note

* remove stupid return

* Update primitives/io/src/lib.rs

Co-Authored-By: Bastian Köcher <[email protected]>

* Update primitives/io/src/lib.rs

Co-Authored-By: Bastian Köcher <[email protected]>

* fix wording

* bump spec_version

Co-authored-by: cheme <[email protected]>
Co-authored-by: Bastian Köcher <[email protected]>