Support Boa nightly version

You can get nightly releases from https://github.com/boa-dev/boa/releases/tag/nightly
This adds support for installing them with `esvu install boa@nightly`.
The filenames are somewhat different.

Author: ptomato

src/engines/boa.js

@@ -10,14 +10,18 @@ const { platform } = require('../common');
 
 const binaryName = platform.startsWith('win') ? 'boa.exe' : 'boa';
 
-function getFilename() {
+function getFilename(version) {
+  const isNightly = version === 'nightly';
   switch (platform) {
     case 'darwin-x64':
-      return 'boa-macos-amd64';
+      return isNightly ? 'boa-x86_64-apple-darwin' : 'boa-macos-amd64';
     case 'linux-x64':
-      return 'boa-linux-amd64';
+      return isNightly ? 'boa-x86_64-unknown-linux-gnu' : 'boa-linux-amd64';
     case 'win32-x64':
-      return 'boa-windows-amd64.exe';
+      return isNightly ? 'boa-x86_64-pc-windows-msvc.exe' : 'boa-windows-amd64.exe';
+    case 'darwin-arm64':
+      if (isNightly) return 'boa-aarch64-apple-darwin';
+      // fall through
     default:
       throw new Error(`No Boa builds available for ${platform}`);
   }
@@ -39,7 +43,7 @@ class BoaInstaller extends Installer {
   }
 
   getDownloadURL(version) {
-    return `https://github.com/boa-dev/boa/releases/download/${version}/${getFilename()}`;
+    return `https://github.com/boa-dev/boa/releases/download/${version}/${getFilename(version)}`;
   }
 
   async extract() {