Add Flint create and refresh index SQL support

[dai-chen]

Description

1. Add SQL support for create and refresh skipping index statement. Please find SQL syntax and example in https://github.com/dai-chen/sql-1/blob/add-create-skipping-index-sql-statement/flint/docs/index.md#sql
2. Rename skipping kind to match its name in SQL grammar
3. Add check for manual refresh on incremental refreshing index

Issues Resolved

opensearch-project/opensearch-spark#2

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

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[codecov]

Codecov Report

Merging #1800 (ba56339) into feature/flint (91b2a06) will not change coverage.
The diff coverage is n/a.

@@               Coverage Diff                @@
##             feature/flint    #1800   +/-   ##
================================================
  Coverage            97.19%   97.19%           
  Complexity            4107     4107           
================================================
  Files                  371      371           
  Lines                10464    10464           
  Branches               706      706           
================================================
  Hits                 10170    10170           
  Misses                 287      287           
  Partials                 7        7           

Flag	Coverage Δ
sql-engine	97.19% <ø> (ø)

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