feat: add especial symbols to mi tag implementation

src/converters/mathml-interfaces-to-latex/mathml-tag-to-latex/mathml-tags/MI.ts

@@ -1,4 +1,6 @@
 import { MathMLTag } from './MathMLTag';
+import { allMathSymbolsByChar } from '../../../../syntax/allMathSymbolsByChar';
+import { allMathSymbolsByGlyph } from '../../../../syntax/allMathSymbolsByGlyph';
 
 export class MI extends MathMLTag {
   constructor(value: string, attributes: Record<string, string>, children: MathMLTag[]) {
@@ -7,6 +9,33 @@ export class MI extends MathMLTag {
 
   convert(): string {
     const normalizedValue = this._normalizeWhiteSpaces(this._value);
-    return normalizedValue.trim();
+    if (normalizedValue === ' ') return Character.apply(normalizedValue);
+
+    const trimmedValue = normalizedValue.trim();
+    return Character.apply(trimmedValue);
+  }
+}
+
+class Character {
+  private _value: string;
+
+  constructor(value: string) {
+    this._value = value;
+  }
+
+  static apply(value: string): string {
+    return new Character(value)._apply();
+  }
+
+  private _apply(): string {
+    return this._findByCharacter() || this._findByGlyph() || this._value;
+  }
+
+  private _findByCharacter(): string | undefined {
+    return allMathSymbolsByChar[this._value];
+  }
+
+  private _findByGlyph(): string | undefined {
+    return allMathSymbolsByGlyph[this._value];
   }
 }