Issues with OpenGLSurface.color_by_code() and color_by_xyz_func()

## Description of bug / unexpected behavior
I'm trying to color an OpenGLSurface based on coordinates and I noticed multiple issues with the differents methods :
- the color_by_code() function can't do anything. Looking at the implementation, it seems that it's editing the shader_wrapper.program_code attribute to change the surface shader but the shader_wrapper attached to the mobject is re-initialised by the get_shader_wrapper() method of OpengGLSurface each time the mobject is rendered. This means that the shaders in the program_code attribute are reloaded from the files each frame which make it impossible to edit them.

- editing directly the finalize_color.glsl shader file can effectively modify the surface color but the coordinates passed in the function seem to be screen space coordinates. Maybe it would be more usefull to put the "///// INSERT COLOR FUNCTION HERE /////" comment which is replaced by the users code in a function that has access to world space coordinates.

- the color_by_xyz_func() method is using the get_colormap_list() method that does not exists

## Expected behavior

## How to reproduce the issue

Code for reproducing the problem

```py
from manim import *
from manim.opengl import *
import numpy as np
class Test(Scene):
def construct(self):
surface = OpenGLSurface(lambda u, v: (u, v, np.cos(u) + np.sin(v)),
u_range=(-5, 5),
v_range=(-5, 5),
color=BLUE,
)
self.play(Create(surface))
surface.set_color_by_code("color = vec4(point.x, point.y, point.z, 1);")
print(surface.get_shader_wrapper().program_code["fragment_shader"])
self.interactive_embed()
```

## Additional media files

Images/GIFs

Editing the finalize_color.glsl file is working but the coordinates are screen space coordinates :

## Logs
Terminal output

Part of printed program_code after modifying the shader with color_by_code(), the comment should have been replaced :
```
vec4 finalize_color(vec4 color,
vec3 point,
vec3 unit_normal,
vec3 light_coords,
float gloss,
float shadow){
///// INSERT COLOR FUNCTION HERE /////
// The line above may be replaced by arbitrary code snippets, as per
// the method Mobject.set_color_by_code
return add_light(color, point, unit_normal, light_coords, gloss, shadow);
}
```

## System specifications

System Details

- OS (with version, e.g., Windows 10 v2004 or macOS 10.15 (Catalina)): Windows 10
- RAM: 4Go
- Python version (`python/py/python3 --version`): 3.9
- Installed modules (provide output from `pip list`):
```
Package Version
------------------ -----------
asttokens 3.0.0
av 13.1.0
beautifulsoup4 4.13.3
click 8.1.8
cloup 3.0.5
colorama 0.4.6
decorator 5.1.1
exceptiongroup 1.2.2
executing 2.2.0
glcontext 3.0.0
importlib_metadata 8.6.1
ipython 8.18.1
isosurfaces 0.1.2
jedi 0.19.2
manim 0.19.0
ManimPango 0.6.0
mapbox_earcut 1.0.3
markdown-it-py 3.0.0
matplotlib-inline 0.1.7
mdurl 0.1.2
moderngl 5.12.0
moderngl-window 3.1.1
networkx 3.2.1
numpy 2.0.2
parso 0.8.4
pillow 11.1.0
pip 23.2.1
prompt_toolkit 3.0.50
pure_eval 0.2.3
pycairo 1.27.0
pydub 0.25.1
pyglet 2.1.2
pyglm 2.8.0
Pygments 2.19.1
rich 13.9.4
scipy 1.13.1
screeninfo 0.8.1
setuptools 68.2.0
skia-pathops 0.8.0.post2
soupsieve 2.6
srt 3.5.3
stack-data 0.6.3
svgelements 1.9.6
tqdm 4.67.1
traitlets 5.14.3
typing_extensions 4.12.2
watchdog 6.0.0
wcwidth 0.2.13
wheel 0.41.2
zipp 3.21.0

```

LaTeX details

+ LaTeX distribution (e.g. TeX Live 2020):
+ Installed LaTeX packages:

## Additional comments

Start by reading OpenGLSurface.get_shader_wrapper(), set_color_by_code(), and color_by_xyz_func(), then inspect finalize_color.glsl and the reproduced program_code output. Done means color_by_code() persists its shader change across rendering, color functions receive the intended coordinates, and color_by_xyz_func() no longer calls the missing get_colormap_list() method.

Written by the indexing model from the issue text.