Update MD051/link-fragments to support id attributes on non-a elements (fixes #538).

The `name` is only an anchor on `a` elements, but `id` is a universal
attribute on all elements.

Also fix match on id/name to be complete, not just a suffix.

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

@@ -20950,7 +20950,7 @@ Generated by [AVA](https://avajs.dev).
             31,
           ],
           fixInfo: null,
-          lineNumber: 132,
+          lineNumber: 144,
           ruleDescription: 'Link fragments should be valid',
           ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md051',
           ruleNames: [
@@ -20966,7 +20966,7 @@ Generated by [AVA](https://avajs.dev).
             36,
           ],
           fixInfo: null,
-          lineNumber: 134,
+          lineNumber: 146,
           ruleDescription: 'Link fragments should be valid',
           ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md051',
           ruleNames: [
@@ -20982,7 +20982,7 @@ Generated by [AVA](https://avajs.dev).
             28,
           ],
           fixInfo: null,
-          lineNumber: 136,
+          lineNumber: 148,
           ruleDescription: 'Link fragments should be valid',
           ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md051',
           ruleNames: [
@@ -20998,7 +20998,7 @@ Generated by [AVA](https://avajs.dev).
             18,
           ],
           fixInfo: null,
-          lineNumber: 138,
+          lineNumber: 150,
           ruleDescription: 'Link fragments should be valid',
           ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md051',
           ruleNames: [
@@ -21014,7 +21014,55 @@ Generated by [AVA](https://avajs.dev).
             21,
           ],
           fixInfo: null,
-          lineNumber: 140,
+          lineNumber: 152,
+          ruleDescription: 'Link fragments should be valid',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md051',
+          ruleNames: [
+            'MD051',
+            'link-fragments',
+          ],
+        },
+        {
+          errorContext: '[Invalid](#name-for-other-element)',
+          errorDetail: null,
+          errorRange: [
+            1,
+            34,
+          ],
+          fixInfo: null,
+          lineNumber: 154,
+          ruleDescription: 'Link fragments should be valid',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md051',
+          ruleNames: [
+            'MD051',
+            'link-fragments',
+          ],
+        },
+        {
+          errorContext: '[Invalid](#name-should-be-ignored)',
+          errorDetail: null,
+          errorRange: [
+            1,
+            34,
+          ],
+          fixInfo: null,
+          lineNumber: 156,
+          ruleDescription: 'Link fragments should be valid',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md051',
+          ruleNames: [
+            'MD051',
+            'link-fragments',
+          ],
+        },
+        {
+          errorContext: '[Invalid](#not-an-id-should-be-ignored)',
+          errorDetail: null,
+          errorRange: [
+            1,
+            39,
+          ],
+          fixInfo: null,
+          lineNumber: 158,
           ruleDescription: 'Link fragments should be valid',
           ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md051',
           ruleNames: [
@@ -21027,7 +21075,7 @@ Generated by [AVA](https://avajs.dev).
           errorDetail: null,
           errorRange: null,
           fixInfo: null,
-          lineNumber: 142,
+          lineNumber: 160,
           ruleDescription: 'Link fragments should be valid',
           ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md051',
           ruleNames: [
@@ -21090,6 +21138,10 @@ Generated by [AVA](https://avajs.dev).
       ␊
       [Valid](#HREFandID)␊
       ␊
+      [Valid](#id-for-other-element)␊
+      ␊
+      [Valid](#id-after-name)␊
+      ␊
       [Valid][goodref]␊
       ␊
       ### Valid H3 Heading␊
@@ -21163,6 +21215,14 @@ Generated by [AVA](https://avajs.dev).
       ␊
       <A href="https://example.com" id="HREFandID">Text</A>␊
       ␊
+      <p id="id-for-other-element"></p>␊
+      ␊
+      <p name="name-for-other-element"></p>␊
+      ␊
+      <input name="name-should-be-ignored" id="id-after-name">␊
+      ␊
+      <a data-id="not-an-id-should-be-ignored">␊
+      ␊
       [goodref]: #namedlink␊
       ␊
       ## Invalid Fragments␊
@@ -21177,6 +21237,12 @@ Generated by [AVA](https://avajs.dev).
       ␊
       [Invalid](#hrefandid) {MD051}␊
       ␊
+      [Invalid](#name-for-other-element) {MD051}␊
+      ␊
+      [Invalid](#name-should-be-ignored) {MD051}␊
+      ␊
+      [Invalid](#not-an-id-should-be-ignored) {MD051}␊
+      ␊
       [Invalid][badref] {MD051}␊
       ␊
       [badref]: #missing␊