api: client and server support `BatchScanRegions`

[you06]

What problem does this PR solve?

Issue Number: close #8307 ref pingcap/tidb#53850

What is changed and how does it work?

Add an interface BatchScanRegions which support scanning regions with non-continuous ranges.

Add `BatchScanRegions` interface for pd-client.

Check List

Tests

• Unit test
• Manual test
  • When loading non-continuous regions in TiDB's coprocessor, this PR optimize the duration from 81.5ms to 2.7ms.

Code changes

Side effects

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• PR to update pingcap/tiup:
• Need to cherry-pick to the release branch

Release note

support `BatchScanRegions` for pd-client.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 80.00000% with 29 lines in your changes missing coverage. Please review.

Project coverage is 77.32%. Comparing base (8c2bb02) to head (d19d0b5).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #8300 +/- ## ========================================== - Coverage 77.42% 77.32% -0.11% ========================================== Files 470 470 Lines 61360 61495 +135 ========================================== + Hits 47510 47550 +40 - Misses 10288 10389 +101 + Partials 3562 3556 -6 ``` | [Flag](https://app.codecov.io/gh/tikv/pd/pull/8300/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/tikv/pd/pull/8300/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv) | `77.32% <80.00%> (-0.11%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv#carryforward-flags-in-the-pull-request-comment) to find out more.

[HuSharp]

And please create an issue to remove do-not-merge/needs-linked-issue label :)

[okJiang]

/test pull-integration-realcluster-test

[ti-chi-bot[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: HuSharp, JmPotato

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/tikv/pd/blob/master/OWNERS)~~ [HuSharp,JmPotato] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[ti-chi-bot[bot]]

[LGTM Timeline notifier]

Timeline:

• 2024-06-18 05:51:39.448539639 +0000 UTC m=+94025.934028468: :ballot_box_with_check: agreed by JmPotato.
• 2024-06-19 04:50:04.528853776 +0000 UTC m=+176731.014342603: :ballot_box_with_check: agreed by HuSharp.

[HuSharp]

/hold

[HuSharp]

/unhold