Support loading files if 'ggml' is found anywhere in the name not just at (#1001)

the beginning and add deprecated flag to models.json so older versions will
show a model, but later versions don't. This will allow us to transition
away from models < ggmlv2 and still allow older installs of gpt4all to work.

gpt4all-chat/download.h

@@ -23,6 +23,7 @@ struct ModelInfo {
     Q_PROPERTY(bool isChatGPT MEMBER isChatGPT)
     Q_PROPERTY(QString description MEMBER description)
     Q_PROPERTY(QString requiresVersion MEMBER requiresVersion)
+    Q_PROPERTY(QString deprecatedVersion MEMBER deprecatedVersion)
     Q_PROPERTY(QString url MEMBER url)
 
 public:
@@ -38,6 +39,7 @@ public:
     bool isChatGPT = false;
     QString description;
     QString requiresVersion;
+    QString deprecatedVersion;
     QString url;
 };
 Q_DECLARE_METATYPE(ModelInfo)