Position the cursor at the beginning of the next block when a block is deleted

This also changes the behavior when blocks are moved.
Add tests for the deleteBlock command.

tests/delete-block.spec.js

@@ -0,0 +1,44 @@
+import {expect, test} from "@playwright/test";
+import {HeynotePage} from "./test-utils.js";
+
+import { AUTO_SAVE_INTERVAL } from "../src/common/constants.js"
+import { NoteFormat } from "../src/common/note-format.js"
+
+
+let heynotePage
+
+test.beforeEach(async ({page}) => {
+    heynotePage = new HeynotePage(page)
+    await heynotePage.goto()
+
+    expect((await heynotePage.getBlocks()).length).toBe(1)
+    await heynotePage.setContent(`
+∞∞∞text
+Block A
+∞∞∞markdown
+Block B
+∞∞∞text
+Block C`)
+    await page.waitForTimeout(100)
+})
+
+test("delete first block", async ({page}) => {
+    await heynotePage.setCursorPosition(10)
+    await page.locator("body").press(heynotePage.agnosticKey("Mod+Shift+D"))
+    await page.waitForTimeout(50)
+    expect(await heynotePage.getCursorPosition()).toBe(13)
+})
+
+test("delete middle block", async ({page}) => {
+    await heynotePage.setCursorPosition(32)
+    await page.locator("body").press(heynotePage.agnosticKey("Mod+Shift+D"))
+    await page.waitForTimeout(50)
+    expect(await heynotePage.getCursorPosition()).toBe(25)
+})
+
+test("delete last block", async ({page}) => {
+    await heynotePage.setCursorPosition(52)
+    await page.locator("body").press(heynotePage.agnosticKey("Mod+Shift+D"))
+    await page.waitForTimeout(50)
+    expect(await heynotePage.getCursorPosition()).toBe(36)
+})