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

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

src/sql/postgres/PostgresCachedStructure.zig

@@ -0,0 +1,34 @@
+structure: JSC.Strong.Optional = .empty,
+// only populated if more than JSC.JSC__JSObject__maxInlineCapacity fields otherwise the structure will contain all fields inlined
+fields: ?[]JSC.JSObject.ExternColumnIdentifier = null,
+
+pub fn has(this: *@This()) bool {
+    return this.structure.has() or this.fields != null;
+}
+
+pub fn jsValue(this: *const @This()) ?JSC.JSValue {
+    return this.structure.get();
+}
+
+pub fn set(this: *@This(), globalObject: *JSC.JSGlobalObject, value: ?JSC.JSValue, fields: ?[]JSC.JSObject.ExternColumnIdentifier) void {
+    if (value) |v| {
+        this.structure.set(globalObject, v);
+    }
+    this.fields = fields;
+}
+
+pub fn deinit(this: *@This()) void {
+    this.structure.deinit();
+    if (this.fields) |fields| {
+        this.fields = null;
+        for (fields) |*name| {
+            name.deinit();
+        }
+        bun.default_allocator.free(fields);
+    }
+}
+
+// @sortImports
+
+const bun = @import("bun");
+const JSC = bun.JSC;