Prefix sample type menu entry ids with "sampletype-".

Previously, we would use the sample type name as the HTML id for the
corresponding menu entry. However some profiles contain sample type
names that conflict with other HTML ids we use (in particular, the
sample type name "sample" conflicted with a different id). Remove this
name clash by prefixing every menu entry with "sampletype-".

some profiles caused the Javascript to break bec

internal/driver/html/common.js

@@ -563,11 +563,11 @@ function viewer(baseUrl, nodes, options) {
     return str.replace(/([\\\.?+*\[\](){}|^$])/g, '\\$1');
   }
 
-  function setSampleIndexLink(id) {
-    const elem = document.getElementById(id);
+  function setSampleIndexLink(si) {
+    const elem = document.getElementById('sampletype-' + si);
     if (elem != null) {
       setHrefParams(elem, function (params) {
-        params.set("si", id);
+        params.set("si", si);
       });
     }
   }

internal/driver/html/header.html

@@ -28,7 +28,7 @@ <h1><a href="./">pprof</a></h1>
     </div>
     <div class="submenu">
       {{range .SampleTypes}}
-      <a href="?si={{.}}" id="{{.}}">{{.}}</a>
+      <a href="?si={{.}}" id="sampletype-{{.}}">{{.}}</a>
       {{end}}
     </div>
   </div>