refactor(postgres) improve postgres code base (#20808)

Co-authored-by: cirospaciari <6379399+cirospaciari@users.noreply.github.com>

src/sql/postgres/protocol/BackendKeyData.zig

@@ -0,0 +1,20 @@
+process_id: u32 = 0,
+secret_key: u32 = 0,
+pub const decode = DecoderWrap(BackendKeyData, decodeInternal).decode;
+
+pub fn decodeInternal(this: *@This(), comptime Container: type, reader: NewReader(Container)) !void {
+    if (!try reader.expectInt(u32, 12)) {
+        return error.InvalidBackendKeyData;
+    }
+
+    this.* = .{
+        .process_id = @bitCast(try reader.int4()),
+        .secret_key = @bitCast(try reader.int4()),
+    };
+}
+
+// @sortImports
+
+const BackendKeyData = @This();
+const DecoderWrap = @import("./DecoderWrap.zig").DecoderWrap;
+const NewReader = @import("./NewReader.zig").NewReader;