feat(blocksync): sort peers by download rate & multiple requests for …

…closer blocks (backport cometbft#2475) (cometbft#2576)

This is an automatic backport of pull request cometbft#2475 done by
[Mergify](https://mergify.com).
Cherry-pick of f8366fc has failed:
```
On branch mergify/bp/v0.38.x/pr-2475
Your branch is up to date with 'origin/v0.38.x'.

You are currently cherry-picking commit f8366fc.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	new file:   .changelog/unreleased/improvements/2475-blocksync-2nd-request.md
	new file:   .changelog/unreleased/improvements/2475-blocksync-no-block-response.md
	new file:   .changelog/unreleased/improvements/2475-blocksync-sort-peers.md
	modified:   blocksync/reactor.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   blocksync/pool.go

```


To fix up this pull request, you can check it out locally. See
documentation:
https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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---------

Co-authored-by: Anton Kaliaev <[email protected]>

.changelog/unreleased/improvements/2475-blocksync-2nd-request.md

@@ -0,0 +1,3 @@
+- `[blocksync]` Request a block from peer B if we are approaching pool's height
+  (less than 50 blocks) and the current peer A is slow in sending us the
+  block [\#2475](https://github.com/cometbft/cometbft/pull/2475)

.changelog/unreleased/improvements/2475-blocksync-no-block-response.md

@@ -0,0 +1,3 @@
+- `[blocksync]` Request the block N from peer B immediately after getting
+  `NoBlockResponse` from peer A
+  [\#2475](https://github.com/cometbft/cometbft/pull/2475)

.changelog/unreleased/improvements/2475-blocksync-sort-peers.md

@@ -0,0 +1,2 @@
+- `[blocksync]` Sort peers by download rate (the fastest peer is picked first)
+  [\#2475](https://github.com/cometbft/cometbft/pull/2475)