perf(map): refactor the representation of MapRef to reduce copying

[xxchan]

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What's changed and what's your intention?

resolve #17863

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[xxchan]

• perf(map): refactor the representation of MapRef to reduce copying #17864 👈
• feat: support parsing map type: map(k,v) #17860 : 2 other dependent PRs (#17980 , #17986 )
• feat: add map type to scalar/array/expr #17690
• refactor(types): simplify ArrayImpl::from_protobuf #17763
• main

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