[Enhancement] Ranking window function support pushing down eq predicate

[liuyehcf]

What type of PR is this：

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Which issues of this PR fixes ：

Fixes #5885

Problem Summary(Required) ：

This pr is a continuate work of #5886, #6118, #6119, #6120 and #6411. For the following query, relop can be <=, < and =, <=, < are supported in the previous work, and this pr, we take = into consideration.

select * from (
    select *, rank() over (partition by v2 order by v3) as rk from t0
) sub_t0
where rk relop 5;

Checklist:

• I have added test cases for my bug fix or my new feature
• I have added user document for my new feature or new function

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

0.0% Coverage
0.0% Duplication

[wanpengfei-git]

[FE PR Coverage Check]

😍 pass : 2 / 2 (100.00%)

file detail

	path	covered_line	new_line	coverage	not_covered_line_detail
🔵	com/starrocks/sql/optimizer/rule/transformation/PushDownPredicateRankingWindowRule.java	2	2	100.00%	[]