Refactor TexTemplate (#3520)

* Refactor `TexTemplate`

* Add tests, refactor some things

* Fixed Some tests

* Move typing imports

* Fix remaining tests

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: JasonGrace2282 <[email protected]>
Co-authored-by: Jason Grace <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: 3 people

manim/_config/utils.py

@@ -28,7 +28,7 @@
 from manim import constants
 from manim.constants import RendererType
 from manim.utils.color import ManimColor
-from manim.utils.tex import TexTemplate, TexTemplateFromFile
+from manim.utils.tex import TexTemplate
 
 if TYPE_CHECKING:
     from enum import EnumMeta
@@ -833,7 +833,7 @@ def digest_args(self, args: argparse.Namespace) -> Self:
 
         # Handle --tex_template
         if args.tex_template:
-            self.tex_template = TexTemplateFromFile(tex_filename=args.tex_template)
+            self.tex_template = TexTemplate.from_file(args.tex_template)
 
         if (
             self.renderer == RendererType.OPENGL
@@ -1756,19 +1756,19 @@ def tex_template(self) -> TexTemplate:
         if not hasattr(self, "_tex_template") or not self._tex_template:
             fn = self._d["tex_template_file"]
             if fn:
-                self._tex_template = TexTemplateFromFile(tex_filename=fn)
+                self._tex_template = TexTemplate.from_file(fn)
             else:
                 self._tex_template = TexTemplate()
         return self._tex_template
 
     @tex_template.setter
-    def tex_template(self, val: TexTemplateFromFile | TexTemplate) -> None:
-        if isinstance(val, (TexTemplateFromFile, TexTemplate)):
+    def tex_template(self, val: TexTemplate) -> None:
+        if isinstance(val, TexTemplate):
             self._tex_template = val
 
     @property
     def tex_template_file(self) -> Path:
-        """File to read Tex template from (no flag).  See :class:`.TexTemplateFromFile`."""
+        """File to read Tex template from (no flag).  See :class:`.TexTemplate`."""
         return self._d["tex_template_file"]
 
     @tex_template_file.setter