feat: Support \Braket, \set, and \Set (#3214)

* feat: Support \Braket, \set, and \Set

* Update screenshots.

* Rewrite to redefine | via macros

* Update screenshot after merge

* Rename \bra@ket@one -> \bra@set

* Fix spacing in \set and \Set to match braket.sty

* Add || and \| support

* Update tests

* Update screenshots

Co-authored-by: Ron Kok <ronkok@comcast.net>

test/katex-spec.js

@@ -3610,6 +3610,26 @@ describe("A macro expander", function() {
     it("should expand \\Ket as expected", () => {
         expect`\Ket{\psi}`.toParseLike`\left|\psi\right\rangle`;
     });
+
+    it("should expand \\Braket as expected", () => {
+        expect`\Braket{ ϕ | \frac{∂^2}{∂ t^2} | ψ }`.toParseLike`\left\langle ϕ\,\middle\vert\,\frac{∂^2}{∂ t^2}\,\middle\vert\, ψ\right\rangle`;
+    });
+
+    it("should expand \\set as expected", () => {
+        expect`\set{x|x<5|S|}`.toParseLike`\{\,x\mid x<5|S|\,\}`;
+        // \set doesn't support special || or \| handling
+        expect`\set{x||x<5|S|}`.toParseLike`\{\,x\mid |x<5|S|\,\}`;
+        expect`\set{x\|x<5|S|}`.toParseLike`\{\,x\|x<5\mid S|\,\}`;
+    });
+
+    it("should expand \\Set as expected", () => {
+        expect`\Set{ x | x<\frac 1 2 |S| }`
+        .toParseLike`\left\{\: x\;\middle\vert\; x<\frac 1 2 |S| \:\right\}`;
+        expect`\Set{ x || x<\frac 1 2 |S| }`
+        .toParseLike`\left\{\: x\;\middle\Vert\; x<\frac 1 2 |S| \:\right\}`;
+        expect`\Set{ x \| x<\frac 1 2 |S| }`
+        .toParseLike`\left\{\: x\;\middle\Vert\; x<\frac 1 2 |S| \:\right\}`;
+    });
 });
 
 describe("\\tag support", function() {

test/screenshotter/ss_data.yaml

@@ -119,12 +119,12 @@ DeepFontSizing:
     nolatex: \Huge inside \dfrac doesn't work, needs an extra {…}
 DelimiterSizing: |
     \bigl\uparrow\Bigl\downarrow\biggl\updownarrow
-    \Biggl\Uparrow\Biggr\Downarrow\biggr\langle\Bigr\}\bigr\rfloor \\
+    \Biggl\Uparrow\Biggr\Downarrow\biggr\langle\Bigr\}\bigr\rfloor\; \Set{ x | x<\frac 1 2 } \\
     \begin{pmatrix}
         a & b & c\\
         a & b & c\\
         a & b & c\\
-    \end{pmatrix}
+    \end{pmatrix}\; \Braket{ ϕ | \frac{∂^2}{∂ t^2} | ψ } \\
 DisplayMode:
     tex: \sum_{i=0}^\infty \frac{1}{i}
     pre: pre