feat: replicate Postgres array types

[fanyang01]

In this PR, array-type columns in Postgres are replicated as DuckDB LIST columns (rather than ARRAY columns, as Postgres does not enforce fixed sizes or dimensions for array values). Additionally, querying LIST columns via the Postgres protocol is supported by mapping DuckDB's LIST types to Postgres' array types.

Resolves #229

[Copilot]

Copilot reviewed 5 out of 7 changed files in this pull request and generated no comments.

Files not reviewed (2)

• pgserver/logrepl/replication.go: Evaluated as low risk
• pgserver/duck_handler.go: Evaluated as low risk

Comments suppressed due to low confidence (2)

pgtest/framework.go:231

• The change from StringFixed(val.Exp * -1) to String() might affect the precision of the numeric value representation. Consider retaining the original precision handling.

decStr := decimal.NewFromBigInt(val.Int, val.Exp).String()

pgtest/framework.go:290

• Trimming trailing zeros and then converting back to a decimal might alter the intended precision of the values. Ensure this change does not affect the precision requirements.

s := d.String() // trim trailing zeros