fix(databasesql): expand DSN parsing to cover libpq KV, MySQL no-parens, and SQLite URI formats

[pradhyum6144]

Summary

Fixes #460.

Three DSN formats were silently producing empty db.name / server.address attributes:

Driver	Format	Example
postgres / pgx	libpq key=value	host=db.example.com port=5432 dbname=prod
mysql	host not parenthesised	user:pass@tcp:3306/mydb
sqlite3	file: URI scheme	file:test.db?cache=shared

Changes

• New dsnparse sub-package (pkg/instrumentation/databasesql/dsnparse/) — isolates all parsing logic so it can be compiled and tested without the otelc-injected fields on sql.DB.
• ParseDSN(driver, dsn string) DSNInfo — driver-dispatched parser returning structured {Host, Port, DBName}. Supports postgres, pgx, postgresql, mysql, sqlite3, sqlite, sqlserver, mssql, clickhouse, godror, oracle, oci8, go-oci8.
• PostgreSQL: handles both RFC 3986 URL and libpq key=value connection strings (including single-quoted values with backslash escapes).
• MySQL: handles both the standard proto(host:port)/dbname form and the non-standard form without parentheses; Unix socket paths (unix(/tmp/mysql.sock)) return an empty port.
• SQLite: extracts DBName from file: URIs, :memory:, and bare filenames/paths.
• SQL Server, ClickHouse, Oracle: URL and ADO.NET / user@host/service forms.
• parse.go in package db is now a thin shim that re-exports ParseDSN, ParseDbName, and the internal LegacyParseDSN shim unchanged.
• 60+ table-driven tests covering URL, key-value, and edge cases for each driver; three sub-tests are explicitly named *PreviouslyFailing to document the regression.

Test plan

• go test -C pkg/instrumentation/databasesql ./dsnparse/... — all tests pass
• Verify db.name and server.address attributes appear in traces when connecting with each of the three previously-failing DSN formats

[txabman42]

@pradhyum6144 duplicated, there is already a PR trying to solve #460.

Since you already have context about the problem, feel free to review the other PR and align approaches.