feat: Support Struct type in approx_distinct

[mkleen]

Which issue does this PR close?

• Relates to Support more types for approx_distinct function #22989 but does not close it. More types are coming.

Rationale for this change

• Support the Arrow type Struct type for approx_distinct

What changes are included in this PR?

• Enable HLLAccumulator and HllGroupsAccumulator to support Struct
• Tests for the non-grouped and grouped path as part of aggregate.slt

Are these changes tested?

Yes and results are compared to DuckDB:

D CREATE TABLE approx_distinct_struct_test AS SELECT * FROM (VALUES
    (1, {'a': 1, 'b': 2}), (1, {'a': 1, 'b': 2}), (1, {'a': 3, 'b': 3}),
    (2, {'a': 4, 'b': 4}), (2, NULL),
    (3, NULL), (3, NULL),
    (4, {'a': 5, 'b': 5})
  ) AS t(g, s);
               
D SELECT approx_count_distinct(s) FROM approx_distinct_struct_test WHERE g = 1;
┌──────────────────────────┐
│ approx_count_distinct(s) │
│          int64           │
├──────────────────────────┤
│            2             │
└──────────────────────────┘
D SELECT g, approx_count_distinct(s) FROM approx_distinct_struct_test GROUP BY g ORDER BY g;
┌───────┬──────────────────────────┐
│   g   │ approx_count_distinct(s) │
│ int32 │          int64           │
├───────┼──────────────────────────┤
│     1 │                        2 │
│     2 │                        1 │
│     3 │                        0 │
│     4 │                        1 │
└───────┴──────────────────────────┘
D SELECT approx_count_distinct(s) FROM approx_distinct_struct_test;
┌──────────────────────────┐
│ approx_count_distinct(s) │
│          int64           │
├──────────────────────────┤
│            4             │
└──────────────────────────┘

Are there any user-facing changes?

Yes, approx_distinct supports now Struct but no breaking changes.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.66%. Comparing base (7ca6e54) to head (e285b01).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #23663      +/-   ##
==========================================
- Coverage   80.66%   80.66%   -0.01%     
==========================================
  Files        1086     1086              
  Lines      366694   366694              
  Branches   366694   366694              
==========================================
- Hits       295806   295798       -8     
- Misses      53265    53266       +1     
- Partials    17623    17630       +7     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Jefffrey]

thanks @mkleen

[mkleen]

@Jefffrey Thanks!