Fix pink GradientTexture2D

[matheusmdx]

Fix #93759, needs #94864 first.

This pr apply the suggested changes here: #93759 (comment)

[akien-mga]

There's the same const_cast for GradientTexture1D.

@KoBeWi added it in #81137, so it would be important to understand why.

[KoBeWi]

I think that update_now() is supposed to prepare the texture in case you want to get the image while an update is still queued.

EDIT:
Yep, this brings back #66627

[rune-scape]

see my suggested fix: #93759 (comment)

[matheusmdx]

see my suggested fix: #93759 (comment)

I tried to apply this changes but i'm getting an error when i compile, most probably i'm doing something wrong:

gradient_texture.h:

gradient_texture.cpp:

Sorry if is some silly error, i'm don't have much knowledge of c++

[rune-scape]

ive made the same changes and didn't get any compiler error
the error output would be helpful,
keep in mind theres GradientTexture1D and GradientTexture2D and they both have a const_cast

[matheusmdx]

@rune-scape I pushed my changes for this pr can you check the tests results?

[rune-scape]

whoa, i swear i thought i compiled it, but ya im getting the same cryptic errors
i think theres a missing create_custom_callable_function_pointer function for const methods that return void .. in callable_method_pointer.h

[rune-scape]

made a PR (#94864) that fixes that problem and tested that these changes compile with that change

[rune-scape]

this and the other call to update_now() should still be here, just as a regular method call without the const_cast

[matheusmdx]

Changes done, i also updated the pr description to inform about #94864

[akien-mga]

Can be rebased as #94864 was just merged.

[matheusmdx]

Done

[akien-mga]

Note for release management: To cherry-pick this to 4.3, #94864 would need to be cherry-picked first.

[akien-mga]

Thanks!