Fix argument font sizing in \fbox and \raisebox, fix font sizing in \TeX, \LaTeX, \KaTeX (#1787)

* Remove forced \normalsize in \raisebox

Fix #1786 (incorrect size of "E" in `\TeX`) by fixing `\raisebox` to
keep the current font size.  Previously, `\raisebox` was rendering its
second argument as if it were in `\normalsize\textrm{...}`; now,
the argument is just as if it were in `\textrm{...}`.

* Fix screenshots

* New "hbox" argument type to convert box-like arguments

* Review comments

* Fix \fbox to use hbox argument

* Render A in \LaTeX and \KaTeX in \scriptstyle (not \scriptsize)

* Add screenshot test

* Revert .sizing { width: min-content} thanks to #2044

test/__snapshots__/mathml-spec.js.snap

@@ -618,9 +618,13 @@ exports[`A MathML builder should use <mpadded> for raisebox 1`] = `
   <semantics>
     <mrow>
       <mpadded voffset="0.25em">
-        <mtext>
-          b
-        </mtext>
+        <mstyle scriptlevel="0"
+                displaystyle="false"
+        >
+          <mtext>
+            b
+          </mtext>
+        </mstyle>
       </mpadded>
     </mrow>
     <annotation encoding="application/x-tex">

test/screenshotter/ss_data.yaml

@@ -160,7 +160,7 @@ Integrands: |
         \iint + \oiint + \iiint + \oiiint
     \end{array}
 KaTeX:
-    tex: \KaTeX
+    tex: \KaTeX, \large \KaTeX
     nolatex: \KaTeX not supported by LaTeX
 Kern:
     tex: \frac{a\kern{1em}b}{c}a\kern{1em}b\kern{1ex}c\kern{-0.25em}d
@@ -173,7 +173,7 @@ Kern:
 #         \mathrlap{\overbrace{\phantom{a_0+a_1+a_2}}^m}a_0+a_1+a_2
 #     \end{array}
 LargeRuleNumerator: \frac{\textcolor{blue}{\rule{1em}{2em}}}{x}
-LaTeX: \text{\LaTeX}, \text{\TeX}
+LaTeX: \text{\LaTeX}, \text{\TeX}, \large \text{\LaTeX}, \text{\TeX}
 LeftRight: \left( x^2 \right) \left\{ x^{x^{x^{x^x}}} \right.
 LeftRightListStyling: a+\left(x+y\right)-x
 LeftRightMiddle: \left( x^2 \middle/ \right) \left\{ x^{x^{x^{x^x}}} \middle/ y \right.\left(x\middle|y\,\middle|\,z\right)