add uniqThetaSketch

[pingyu]

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Changelog category (leave one):

• New Feature datasketches support in clickhouse #14893

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

• Add uniqThetaSketch to support Theta Sketch in ClickHouse.

Detailed description / Documentation draft:

• Added document at docs/en/sql-reference/aggregate-functions/reference/uniqthetasketch.md

[pingyu]

The failure of build seems to be caused by DataSketches submodule is not checked out.
How can I fix it ? @Avogar

[Avogar]

We should add the needed submodule in this list:

ClickHouse/docker/test/fasttest/run.sh

Line 160 in 30f2d83

SUBMODULES_TO_UPDATE=(

I will do it.

[Avogar]

You also should support case when ENABLE_DATASKETCHES=0 in code. Now it just cannot build with it. Put all logic with submodule under if USE_DATASKETCHES and throw an exception when it's not enabled and uniqThetaSketch is called.
I enabled it by default in fasttest to see other tests. Maybe we should disable it in the future, I will think about it.

[pingyu]

Comments addressed. PTAL, thanks~ @Avogar

[Avogar]

LGTM, some problems with synchronization again, I will fix it and will merge.

[Avogar]

I put all tests with uniqThetaSketch in one file to have an ability to disable it when we cannot use datasketches submodule. Lets wait for the tests and if there are no errors - merge.