feat: Generate DB unique constraints as enums (#3701)

* feat: Generate DB unique constraints as enums

This fixes a TODO from #3409.

coderd/database/gen/dump/main.go

@@ -0,0 +1,95 @@
+package main
+
+import (
+	"bytes"
+	"database/sql"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+
+	"github.com/coder/coder/coderd/database"
+	"github.com/coder/coder/coderd/database/postgres"
+)
+
+func main() {
+	connection, closeFn, err := postgres.Open()
+	if err != nil {
+		panic(err)
+	}
+	defer closeFn()
+
+	db, err := sql.Open("postgres", connection)
+	if err != nil {
+		panic(err)
+	}
+
+	err = database.MigrateUp(db)
+	if err != nil {
+		panic(err)
+	}
+
+	cmd := exec.Command(
+		"docker",
+		"run",
+		"--rm",
+		"--network=host",
+		"postgres:13",
+		"pg_dump",
+		"--schema-only",
+		connection,
+		"--no-privileges",
+		"--no-owner",
+
+		// We never want to manually generate
+		// queries executing against this table.
+		"--exclude-table=schema_migrations",
+	)
+
+	cmd.Env = append(os.Environ(), []string{
+		"PGTZ=UTC",
+		"PGCLIENTENCODING=UTF8",
+	}...)
+	var output bytes.Buffer
+	cmd.Stdout = &output
+	cmd.Stderr = os.Stderr
+	err = cmd.Run()
+	if err != nil {
+		panic(err)
+	}
+
+	for _, sed := range []string{
+		// Remove all comments.
+		"/^--/d",
+		// Public is implicit in the schema.
+		"s/ public\\./ /",
+		// Remove database settings.
+		"s/SET .* = .*;//g",
+		// Remove select statements. These aren't useful
+		// to a reader of the dump.
+		"s/SELECT.*;//g",
+		// Removes multiple newlines.
+		"/^$/N;/^\\n$/D",
+	} {
+		cmd := exec.Command("sed", "-e", sed)
+		cmd.Stdin = bytes.NewReader(output.Bytes())
+		output = bytes.Buffer{}
+		cmd.Stdout = &output
+		cmd.Stderr = os.Stderr
+		err = cmd.Run()
+		if err != nil {
+			panic(err)
+		}
+	}
+
+	dump := fmt.Sprintf("-- Code generated by 'make coderd/database/generate'. DO NOT EDIT.\n%s", output.Bytes())
+	_, mainPath, _, ok := runtime.Caller(0)
+	if !ok {
+		panic("couldn't get caller path")
+	}
+	err = os.WriteFile(filepath.Join(mainPath, "..", "..", "..", "dump.sql"), []byte(dump), 0o600)
+	if err != nil {
+		panic(err)
+	}
+}