fix: Messing static flags in php_impl proc macro

[Norbytus]

If try class static method from php it throws exception

Uncaught Error: Non-static method Test::staticTest()

Cause in proc_macros missing usage of MethodFlags::Static

#[php_class]
#[derive(Default)]
struct Test {}

#[php_impl]
impl Test {
    #[php(constructor)]
    fn new() -> Self {
        Self {}
    }
    /// Declare as static method
    fn static_test() -> String {
        String::from("Hello")
    }
}

<?php

$t = new Test;
Test::staticTest(); // Get exception

In PR i change FnBuilder from single additional modifier with flag abstract to Vec, Myabe we should make uniq Vec, idk)

[Xenira]

Nice catch. Would you mind including an integration test as well.

Will have a closer look at the implementation this evening.