feat(function): Implement map_size function

[forsaken628]

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Summary

Implement map_size function

• Addresses part of Feature: Support map functions #15295

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - Explain why

Type of change

• Bug Fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• Breaking Change (fix or feature that could cause existing functionality not to work as expected)
• Documentation Update
• Refactoring
• Performance Improvement
• Other (please describe):

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This change is 

[b41sh]

LGTM
Hi @forsaken628 This PR seems to be the first time you've contributed to databend, thank you very much for your interest and feel free to keep contributing more code.