Introduce a `#[declare_sql_function]` attribute macro #5060

Job	Run time
Check rustfmt style && run clippy	2m 18s
Check sqlite wasm	1m 53s
Compiletests	1m 30s
Check Minimal supported rust version (1.78.0)	1m 26s
Check (stable, postgres, ubuntu-latest)	8m 16s
Check mysql bundled + Mysql with asan	14m 15s
Check postgres bundled + Postgres with asan	8m 14s
Check (stable, postgres, macos-13)	4m 56s
Check sqlite bundled + Sqlite with asan	3m 52s
Check (stable, postgres, macos-15)	2m 31s
Check (stable, postgres, windows-2025)	19m 33s
Check (stable, postgres, ubuntu-22.04-arm)	8m 1s
Check (stable, sqlite, ubuntu-latest)	4m 3s
Check (stable, sqlite, macos-13)	3m 47s
Check (stable, sqlite, macos-15)	1m 31s
Check (stable, sqlite, windows-2025)	6m 17s
Check (stable, sqlite, ubuntu-22.04-arm)	4m 27s
Check (stable, mysql, ubuntu-latest)	8m 28s
Check (stable, mysql, macos-13)	6m 12s
Check (stable, mysql, macos-15)	4m 20s
Check (stable, mysql, windows-2025)	7m 2s
Check (stable, mysql, ubuntu-22.04-arm)	6m 28s
Check (beta, postgres, ubuntu-latest)	8m 0s
Check (beta, sqlite, ubuntu-latest)	4m 0s
Check (beta, mysql, ubuntu-latest)	8m 11s
Check (nightly, postgres, ubuntu-latest)	5m 6s
Check (nightly, sqlite, ubuntu-latest)	2m 58s
Check (nightly, mysql, ubuntu-latest)	4m 42s
	2h 42m 17s

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