Reimplement MD026/no-trailing-punctuation using micromark tokens, ignore trailing GitHub emoji codes, improve tests (fixes #457).

test/snapshots/markdownlint-test-scenarios.js.md

@@ -14772,6 +14772,40 @@ Generated by [AVA](https://avajs.dev).
       `,
     }
 
+## headings-with-emoji.md
+
+> Snapshot 1
+
+    {
+      errors: [],
+      fixed: `# headings-with-emoji␊
+      ␊
+      ## Known Issues :bug:␊
+      ␊
+      ## Love :heartpulse:␊
+      ␊
+      ## :tada:␊
+      ␊
+      ## :checkered_flag:␊
+      ␊
+      ## :clock930:␊
+      ␊
+      ## :t-rex:␊
+      ␊
+      ## Boba:bubble_tea:␊
+      ␊
+      <!-- markdownlint-disable heading-style -->␊
+      ␊
+      ## Fix the :bug: ##␊
+      ␊
+      Another :heartpulse:␊
+      --------------------␊
+      ␊
+      :eyes:␊
+      ------␊
+      `,
+    }
+
 ## headings-with-html-entities.md
 
 > Snapshot 1
@@ -14789,7 +14823,7 @@ Generated by [AVA](https://avajs.dev).
             deleteCount: 1,
             editColumn: 31,
           },
-          lineNumber: 22,
+          lineNumber: 24,
           ruleDescription: 'Trailing punctuation in heading',
           ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md026.md',
           ruleNames: [
@@ -14808,7 +14842,7 @@ Generated by [AVA](https://avajs.dev).
             deleteCount: 1,
             editColumn: 34,
           },
-          lineNumber: 24,
+          lineNumber: 26,
           ruleDescription: 'Trailing punctuation in heading',
           ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md026.md',
           ruleNames: [
@@ -14827,7 +14861,7 @@ Generated by [AVA](https://avajs.dev).
             deleteCount: 1,
             editColumn: 31,
           },
-          lineNumber: 26,
+          lineNumber: 28,
           ruleDescription: 'Trailing punctuation in heading',
           ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md026.md',
           ruleNames: [
@@ -14850,6 +14884,8 @@ Generated by [AVA](https://avajs.dev).
       ␊
       ## Copyright 2004 &#x000A9;␊
       ␊
+      ## Copyright 2004 &#X000A9;␊
+      ␊
       ## Copyright 2005 &#169;␊
       ␊
       ## Copyright 2006 &#169; ##␊