[SR SQL Planner Summer Camp] add showSnapshot analyzer

[melt-code]

What type of PR is this：

• [ ] bug
• [x] feature
• [ ] enhancement
• [ ] refactor
• [ ] others

Which issues of this PR fixes ：

Fixes #7951

Problem Summary(Required) ：

add showSnapshot analyzer

[sonarcloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
3 Code Smells

0.0% Coverage
0.0% Duplication

[melt-code]

run starrocks_fe_unittest

[wanpengfei-git]

[FE PR Coverage Check]

:heart_eyes: pass : 62 / 72 (86.11%)

file detail

	path	covered_line	new_line	coverage	not_covered_line_detail
:large_blue_circle:	com/starrocks/sql/ast/AstVisitor.java	0	1	00.00%	[492]
:large_blue_circle:	com/starrocks/sql/analyzer/ShowSnapshotAnalyzer.java	48	56	85.71%	[19, 37, 60, 61, 73, 75, 109, 115]
:large_blue_circle:	com/starrocks/analysis/ShowSnapshotStmt.java	6	7	85.71%	[172]
:large_blue_circle:	com/starrocks/sql/analyzer/Analyzer.java	2	2	100.00%	[]
:large_blue_circle:	com/starrocks/sql/parser/AstBuilder.java	6	6	100.00%	[]

[sonarcloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
3 Code Smells

0.0% Coverage
0.0% Duplication

[melt-code]

run starrocks_admit_test