storage: introduce a couple of replication reports

[andreimatei]

This patch implements the "Insights into Constraint Conformance" RFC
(#38309). At the time of this patch, the RFC is still pending and also
out of date.
The patch introduces the following tables in the system database,
providing information about constraint conformance, replication status
and critical localities (i.e. localities that, were they to become
unavailable, would cause some ranges to lose quorum):

  CREATE TABLE replication_constraint_stats (
      zone_id INT8 NOT NULL,
      subzone_id INT8 NOT NULL,
      type STRING NOT NULL,
      config STRING NOT NULL,
      report_id INT8 NOT NULL,
      violation_start TIMESTAMP NULL,
      violating_ranges INT8 NOT NULL,
      CONSTRAINT "primary" PRIMARY KEY (zone_id ASC, subzone_id ASC, type ASC, config ASC),
      FAMILY "primary" (zone_id, subzone_id, type, config, report_id, violation_start, violating_ranges)
  );

  CREATE TABLE replication_stats (
      zone_id INT8 NOT NULL,
      subzone_id INT8 NOT NULL,
      report_id INT8 NOT NULL,
      total_ranges INT8 NOT NULL,
      unavailable_ranges INT8 NOT NULL,
      under_replicated_ranges INT8 NOT NULL,
      over_replicated_ranges INT8 NOT NULL,
      CONSTRAINT "primary" PRIMARY KEY (zone_id ASC, subzone_id ASC),
      FAMILY "primary" (zone_id, subzone_id, report_id, total_ranges, unavailable_ranges, under_replicated_ranges, over_replicated_ranges)
  );

    CREATE TABLE replication_critical_localities (
      zone_id INT8 NOT NULL,
      subzone_id INT8 NOT NULL,
      locality STRING NOT NULL,
      report_id INT8 NOT NULL,
      at_risk_ranges INT8 NOT NULL,
      CONSTRAINT "primary" PRIMARY KEY (zone_id ASC, subzone_id ASC, locality ASC),
      FAMILY "primary" (zone_id, subzone_id, locality, report_id, at_risk_ranges)
  )

And also a system.report_meta table with metadata for all these reports
(their creation time).

The reports are generated periodically (once a minute by default,
subject to the cluster setting kv.replication_reports.interval) by a job
running on the leaseholder of range 1.
The data is produced by joing range descriptor data from meta2 with zone
config information from the gossiped SystemConfig.

Release note (sql change): The following system tables containing report about
replication status, constraint conformance and critical localities are
introduced: replication_constraint_stats, replication_stats,
replication_critical_localities.

[cockroach-teamcity]

This change is 

[andreimatei]

no review on the PR; developed with @darinpp

bors r+

[craig]

Build failed

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[andreimatei]

failed on logictest timeout - #40572

bors r+

[craig]

Build failed

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[andreimatei]

some sort of a race in a logic test. I think I've fixed it.

bors r+

[craig]

Build succeeded

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