Add unique index support

[dcherednik]

Since 24.1 ydb has option to enable unique constraint. This commit allows to create table with unique constraint or add it by alter table call

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 7.69231% with 12 lines in your changes missing coverage. Please review.

Project coverage is 47.17%. Comparing base (798bb60) to head (f717222).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
...a/tech/ydb/table/description/TableDescription.java	0.00%	4 Missing ⚠️
...src/main/java/tech/ydb/table/impl/BaseSession.java	0.00%	3 Missing and 1 partial ⚠️
...va/tech/ydb/table/settings/AlterTableSettings.java	0.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #309      +/-   ##
============================================
- Coverage     47.24%   47.17%   -0.07%     
  Complexity     1703     1703              
============================================
  Files           304      304              
  Lines         12226    12239      +13     
  Branches       1220     1221       +1     
============================================
- Hits           5776     5774       -2     
- Misses         5997     6010      +13     
- Partials        453      455       +2     

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