fix: parsing composite types that cross a CopyData boundary

[levkk]

The CSV parser we use stripped quotes, leaving a closing quote without an opening one when the record was split between multiple CopyData rows.

[codecov]

Codecov Report

❌ Patch coverage is 97.95918% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pgdog/src/frontend/router/parser/copy.rs	93.33%	2 Missing ⚠️
pgdog/src/backend/server.rs	98.94%	1 Missing ⚠️
pgdog/src/frontend/router/parser/csv/mod.rs	98.59%	1 Missing ⚠️

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