feat: clean-up resharding v2: part 1

[Trisfald]

First part of cleanup of legacy resharding V2 code.

Notes:

• a subset of resharding V2 will remain as it is required by the resharding tool
  • resharding V2 source files have now the _v2 suffix
• for better user experience no changes will be made to resharding config

This is just the beginning.. many other things must be removed as well:

• StateSnapshotType::ForReshardingOnly
• StateChangeCauseView::Resharding
• StateChangesForResharding
• InvalidSplitShardsIds
• ShardSyncStatus::{ReshardingScheduling, ReshardingApplying}
• ReshardingResult
• All resharding metrics
• ApplyResultForResharding
• State_sync::resharding_state_roots
• Various resharding fn in chain.rs
• Resharding handle
• ShardUpdateReason::Resharding
• Reassigning of outgoing receipt in chain/src/store/mod.rs

I think it's better to tackle the other items in different PRs, but I don't have a strong opinion

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 31 lines in your changes missing coverage. Please review.

Project coverage is 71.53%. Comparing base (0e6179a) to head (a0c945f). Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
chain/chain/src/resharding/resharding_v2.rs	0.00%	26 Missing :warning:
tools/database/src/resharding_v2.rs	0.00%	3 Missing :warning:
chain/client/src/sync/state.rs	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #12042 +/- ## ========================================== + Coverage 71.51% 71.53% +0.01% ========================================== Files 814 814 Lines 164513 164405 -108 Branches 164513 164405 -108 ========================================== - Hits 117648 117602 -46 + Misses 41699 41640 -59 + Partials 5166 5163 -3 ``` | [Flag](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | Coverage Δ | | |---|---|---| | [backward-compatibility](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | `0.17% <0.00%> (+<0.01%)` | :arrow_up: | | [db-migration](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | `0.17% <0.00%> (+<0.01%)` | :arrow_up: | | [genesis-check](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | `1.28% <0.00%> (+<0.01%)` | :arrow_up: | | [integration-tests](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | `38.60% <0.00%> (+0.02%)` | :arrow_up: | | [linux](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | `71.31% <0.00%> (+<0.01%)` | :arrow_up: | | [linux-nightly](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | `71.11% <0.00%> (+0.01%)` | :arrow_up: | | [macos](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | `54.16% <0.00%> (+0.06%)` | :arrow_up: | | [pytests](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | `1.54% <0.00%> (+<0.01%)` | :arrow_up: | | [sanity-checks](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | `1.35% <0.00%> (+<0.01%)` | :arrow_up: | | [unittests](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | `65.36% <0.00%> (-0.04%)` | :arrow_down: | | [upgradability](https://app.codecov.io/gh/near/nearcore/pull/12042/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=near) | `0.21% <0.00%> (+<0.01%)` | :arrow_up: | 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=near#carryforward-flags-in-the-pull-request-comment) to find out more.

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