Add setting for subtitle outline size (#375)

Adds a settings allowing for adjusting the thickness of unstyled
subtitle outlines, if outline is enabled.

This is applied for both ExoPlayer & MPV

Closes #179

![outline
Large](https://github.com/user-attachments/assets/dfef74a5-a4d4-49db-a8d2-231e46ab151e)

Dev note: the ExoPlayer implementation is bad code, don't write code
like this. It works though

app/src/main/java/com/github/damontecres/wholphin/util/Media3SubtitleOverride.kt

@@ -0,0 +1,56 @@
+package com.github.damontecres.wholphin.util
+
+import androidx.media3.ui.SubtitleView
+import timber.log.Timber
+import java.lang.reflect.Field
+
+/**
+ * Utility class to override private fields in media3's [SubtitleView]
+ */
+class Media3SubtitleOverride(
+    val outlineThicknessPx: Float,
+) {
+    companion object {
+        private lateinit var outputField: Field
+        private lateinit var classCanvasSubtitleOutput: Class<*>
+        private lateinit var paintersField: Field
+        private lateinit var classSubtitlePainter: Class<*>
+        private lateinit var outlineWidthField: Field
+
+        var initialized: Boolean
+            private set
+
+        init {
+            try {
+                // This is bad times
+                outputField = SubtitleView::class.java.getDeclaredField("output")
+                classCanvasSubtitleOutput = Class.forName("androidx.media3.ui.CanvasSubtitleOutput")
+                paintersField = classCanvasSubtitleOutput.getDeclaredField("painters")
+                classSubtitlePainter = Class.forName("androidx.media3.ui.SubtitlePainter")
+                outlineWidthField = classSubtitlePainter.getDeclaredField("outlineWidth")
+                outputField.isAccessible = true
+                outlineWidthField.isAccessible = true
+                paintersField.isAccessible = true
+                initialized = true
+            } catch (ex: Exception) {
+                Timber.w(ex, "Error initializing")
+                initialized = false
+            }
+        }
+    }
+
+    fun apply(subtitleView: SubtitleView) {
+        try {
+            if (initialized) {
+                // Basically hijack the field that controls the subtitle outline size
+                val canvasSubtitleOutput = outputField.get(subtitleView)
+                val painters = paintersField.get(canvasSubtitleOutput) as List<*>
+                painters.forEach { painter ->
+                    outlineWidthField.set(painter, outlineThicknessPx)
+                }
+            }
+        } catch (ex: Exception) {
+            Timber.w(ex, "Failed to apply")
+        }
+    }
+}