[Editor] Improve curve smoothing for Ink tool (bug 1789443)

- Remove the dependency on fit-curve;
- Improve the way to draw the current line in using a Path2D and
  in clearing only the last part of the curve instead of clearing
  all the canvas;
- Smooth the curve when drawing to avoid to have some changes after
  the drawing ends;
- Make the smoothing a bit less agressive.

test/unit/editor_spec.js

@@ -14,7 +14,6 @@
  */
 
 import { CommandManager } from "../../src/display/editor/tools.js";
-import { fitCurve } from "../../src/display/editor/ink.js";
 
 describe("editor", function () {
   describe("Command Manager", function () {
@@ -91,29 +90,4 @@ describe("editor", function () {
     manager.add({ ...makeDoUndo(5), mustExec: true });
     expect(x).toEqual(11);
   });
-
-  describe("fitCurve", function () {
-    it("should return a function", function () {
-      expect(typeof fitCurve).toEqual("function");
-    });
-
-    it("should compute an Array of bezier curves", function () {
-      const bezier = fitCurve(
-        [
-          [1, 2],
-          [4, 5],
-        ],
-        30,
-        null
-      );
-      expect(bezier).toEqual([
-        [
-          [1, 2],
-          [2, 3],
-          [3, 4],
-          [4, 5],
-        ],
-      ]);
-    });
-  });
 });

test/unit/unit_test.html

@@ -15,7 +15,6 @@
         "pdfjs/": "../../src/",
         "pdfjs-lib": "../../src/pdf.js",
         "pdfjs-web/": "../../web/",
-        "pdfjs-fitCurve": "../../build/dev-fitCurve/fit_curve.js",
         "pdfjs-test/": "../",
 
         "web-annotation_editor_params": "../../web/annotation_editor_params.js",