Isolate the "create editor with keyboard" freetext editor integration tests

This commit reduces the number of freetext editor integration test suite
failures, in full isolation, from 6 to 5 by fixing the following issues
in the "create editor with keyboard" block:

- The second test relied on the first test to enable freetext editing
  mode and put focus on the page (annotation layer). For isolation we
  now do that explicitly in the second test.
- The second test relied on the first test for the editor numbering. For
  isolation we change the editor numbering to the one after initial
  document load.

Moreover, the test names have been updated to clarify with scenario is
being tested, which came up during comparison of the changes against
commit ea5eafa to make sure that we are still testing the originally
intended scenarios (confirmed by disabling the relevant code from the
commit per scenario and noticing the corresponding test failing).

test/integration/freetext_editor_spec.mjs

@@ -2340,20 +2340,19 @@ describe("FreeText Editor", () => {
   describe("Create editor with keyboard", () => {
     let pages;
 
-    beforeAll(async () => {
+    beforeEach(async () => {
       pages = await loadAndWait("empty.pdf", ".annotationEditorLayer");
     });
 
-    afterAll(async () => {
+    afterEach(async () => {
       await closePages(pages);
     });
 
-    it("must create an editor from the toolbar", async () => {
+    it("must create an editor, using Enter/Space keys, with focused toolbar button", async () => {
       await Promise.all(
         pages.map(async ([browserName, page]) => {
           await page.focus("#editorFreeTextButton");
           await page.keyboard.press("Enter");
-
           let editorSelector = getEditorSelector(0);
           await page.waitForSelector(editorSelector, { visible: true });
 
@@ -2394,11 +2393,14 @@ describe("FreeText Editor", () => {
       );
     });
 
-    it("must create an editor with keyboard", async () => {
+    it("must create an editor, using Enter/Space keys, with focused page", async () => {
       await Promise.all(
         pages.map(async ([browserName, page]) => {
+          await switchToFreeText(page);
+
+          await page.focus(".annotationEditorLayer");
           await page.keyboard.press("Enter");
-          let editorSelector = getEditorSelector(2);
+          let editorSelector = getEditorSelector(0);
           await page.waitForSelector(editorSelector, { visible: true });
 
           await moveEditor(page, editorSelector, 10, () => kbBigMoveLeft(page));
@@ -2417,7 +2419,7 @@ describe("FreeText Editor", () => {
           expect(content).withContext(`In ${browserName}`).toEqual(data);
 
           await page.keyboard.press(" ");
-          editorSelector = getEditorSelector(3);
+          editorSelector = getEditorSelector(1);
           await page.waitForSelector(editorSelector, { visible: true });
 
           await moveEditor(page, editorSelector, 10, () =>