feat: name Android BIOS folders out of reach

DraStic keeps its BIOS in its private data and Flycast in Android/data,
which Termux cannot write on Android 11 and later. An installed one is now
named with the files not copied, and a writable Flycast folder is a
standalone copy target.

install.ps1

@@ -11,7 +11,7 @@
 
     $ErrorActionPreference = "Stop"
     $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-    $defaultInstallSha256 = "956eba5f9d01138abda5550973810ccdc1138daa54c9065bf3f04cc0ba051468"
+    $defaultInstallSha256 = "6ae8bdd7bbe9a0c3e6cb2d92947bb4e135e38d6446d206ae30b988a045eaa536"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }