feat: Add constructor visability

[Norbytus]

Add visability in constructor meta, and feature mark constructor as private and protected

Description

• Add MethodFlags to ConstructorMeta
• Relevant or closing issues[ (https://github.com/Add visability to constructor #541)
• I made fast solution, and it could be not neat

Checklist

Check the boxes that apply (put an x in the brackets, like [x]). You can also check boxes after the PR is created.

• I have read the contribution guidelines.
• I have added tests that prove my code works as expected.
• I have added documentation if applicable.
• I have added a migration guide if applicable.

❤️ Thank you for your contribution!

[Norbytus]

@Xenira how i can update guide there wrong doc about private,protected, public
Now

#[php(public)]`, `#[php(protected)]` and `#[php(private)]` - Sets the

Should be

#[php(vis = "public")]`, `#[php(vis = "protected")]` and `#[php(vis = "private")]` - Sets the

[coveralls]

Pull Request Test Coverage Report for Build 16824767628

Details

• 5 of 21 (23.81%) changed or added relevant lines in 4 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.03%) to 27.748%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
crates/macros/src/function.rs	0	3	0.0%
src/builders/class.rs	5	8	62.5%
crates/macros/src/impl_.rs	0	4	0.0%
crates/macros/src/parsing.rs	0	6	0.0%

Files with Coverage Reduction	New Missed Lines	%
crates/macros/src/impl_.rs	1	0.0%

Totals
Change from base Build 16813466135:	-0.03%
Covered Lines:	1156
Relevant Lines:	4166

---

💛 - Coveralls

[Xenira]

@Norbytus see here:

ext-php-rs/guide/src/macros/impl.md

Line 45 in 34caede

- `#[php(public)]`, `#[php(protected)]` and `#[php(private)]` - Sets the visibility of the

[Norbytus]

@Norbytus see here:

ext-php-rs/guide/src/macros/impl.md

Line 45 in 34caede

- `#[php(public)]`, `#[php(protected)]` and `#[php(private)]` - Sets the visibility of the

I see that variant, but it's not working)

error: Unknown field: `private`
   --> tests/src/integration/class/mod.rs:152:11
    |
152 |     #[php(private)]
    |           ^^^^^^^

So i think, maybe we update dock.
But anyway, main thing for this PR it's declare __construct as public, private, protected

[Xenira]

Ye, docs are probably wrong there.

[Xenira]

Thanks, looks good. Just some minor code style suggestions.