refactor: reorganize array expressions in proto

[bcallender]

Array Functions Organization

This PR reorganizes array expressions in the logical plan proto to improve maintainability:

• Groups all array-related expressions together in the LogicalExpr message
• Adds clear section headers and comments to guide future array function additions
• Reserves field number ranges (170-189) specifically for array functions
• Adds new array function message definitions in a dedicated section
• Preserves existing field numbers for backward compatibility

The following array functions are now properly organized:

• Construction: array, array_repeat
• Introspection: array_length
• Element access: array_contains, element_at, array_slice
• Transformation: array_distinct, array_max, array_min, array_sort, array_reverse, array_remove, array_compact, flatten
• Set operations: array_union, array_intersect, array_except, arrays_overlap

This organization makes it easier to find and understand array functions, while providing clear guidance for adding new array functions in the future, laying the ground work for the array operations we will be adding in further downstack PRs.

[bcallender]

• feat: add support for pyspark equivalent explode_outer, posexplode/posexplode_outer (via explode_with_index) #249
• feat: implement regexp_* text functions #247
• feat: add array_* functions #243
• refactor: reorganize array expressions in proto #245 👈 (View in Graphite)
• feat: add support for sum_distinct, count_distinct, approx_count_distinct #242
• main

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[YoungVor]

Looks good to me, since the array_* pr will test that this is all correct. Just had a few nits