Analysis: use reanalyze 2.21.

Use specifically `reanalyze@2.21.0` when starting dead code analysis.
This allows to configure the analysis via `bsconfig.json`.

Author: cristianoc

analysis/tests/bsconfig.json

@@ -1,5 +1,8 @@
 {
   "name": "test",
+  "reanalyze": {
+    "analysis": ["dce"]
+  },
   "sources": [
     {
       "dir": "src",

client/src/commands/dead_code_analysis.ts

@@ -213,7 +213,7 @@ export const runDeadCodeAnalysisWithReanalyze = (
   let currentDocument = window.activeTextEditor.document;
   let cwd = targetDir ?? path.dirname(currentDocument.uri.fsPath);
 
-  let p = cp.spawn("npx", ["reanalyze", "-config"], {
+  let p = cp.spawn("npx", ["reanalyze@2.21.0", "-config"], {
     cwd,
   });