chore(lib): re-organizing the module

This PR refactors a lot of the code in order to have a better organized codebase. If will that I needed to create a second level of submodules, to better distinguish the different parts of this project.

manim_slides/cli/render/commands.py

@@ -0,0 +1,55 @@
+"""Manim Slides' rendering commands."""
+
+import subprocess
+import sys
+
+import click
+
+
+@click.command(
+    context_settings=dict(
+        ignore_unknown_options=True, allow_extra_args=True, help_option_names=("-h",)
+    ),
+    options_metavar="[-h] [--CE|--GL]",
+)
+@click.option(
+    "--CE",
+    is_flag=True,
+    envvar="MANIM_RENDERER",
+    show_envvar=True,
+    help="If set, use Manim Community Edition (CE) renderer. "
+    "If this or ``--GL`` is not set, defaults to CE renderer.",
+)
+@click.option(
+    "--GL",
+    is_flag=True,
+    envvar="MANIMGL_RENDERER",
+    show_envvar=True,
+    help="If set, use ManimGL renderer.",
+)
+@click.argument("args", metavar="[RENDERER_ARGS]...", nargs=-1, type=click.UNPROCESSED)
+def render(ce: bool, gl: bool, args: tuple[str, ...]) -> None:
+    """
+    Render SCENE(s) from the input FILE, using the specified renderer.
+
+    Use ``manim-slides render --help`` to see help information for
+    a specific renderer.
+
+    Alias command to either
+    ``manim render [OPTIONS] [ARGS]...`` or
+    ``manimgl [OPTIONS] [ARGS]...``.
+
+    This is especially useful for two reasons:
+
+    1. You can are sure to execute the rendering command with the same Python environment
+       as for ``manim-slides``.
+    2. You can pass options to the config.
+    """
+    if ce and gl:
+        raise click.UsageError("You cannot specify both --CE and --GL renderers.")
+    if gl:
+        subprocess.run([sys.executable, "-m", "manimlib", *args])
+    else:
+        from manim.cli.render.commands import render as render_ce
+
+        render_ce(args, standalone_mode=False)