Set the text fields font size based on their height

- right now we're using the font size from the pdf itself but we use an other font
  in the annotation layer. So this size doesn't really make sense and leads to bad
  rendering (see pdf in #14928);
- use a sans-serif font for the fields containing text (fix issue #14736);
- remove useless padding in text-based fields (fix issue #14301);
- text fields allow/disallow scrolling bars (see bit 24 in Ff entry), so use this
  value to hide/show scrollbars in annotation layer.

src/shared/util.js

@@ -18,6 +18,10 @@ import "./compatibility.js";
 const IDENTITY_MATRIX = [1, 0, 0, 1, 0, 0];
 const FONT_IDENTITY_MATRIX = [0.001, 0, 0, 0.001, 0, 0];
 
+// Represent the percentage of the height of a single-line field over
+// the font size. Acrobat seems to use this value.
+const LINE_FACTOR = 1.35;
+
 /**
  * Refer to the `WorkerTransport.getRenderingIntent`-method in the API, to see
  * how these flags are being used:
@@ -1162,6 +1166,7 @@ export {
   isArrayBuffer,
   isArrayEqual,
   isAscii,
+  LINE_FACTOR,
   MissingPDFException,
   objectFromMap,
   objectSize,