Go-PIC Alpha v0.1.2 - Extended symbol support

Changes

🚀 Features

• Symbols - Document and support type mapping for basic PIC symbols @pgmitche (#11)
  • this adds support for:

| Symbol |  Description 
|--------|----------------------------
| 9      | Numeric (previously done)
| A      | Alphabetic
| X      | Alphanumeric (previously done)
| V      | Implicit decimal
| S      | Sign
| P      | Assumed decimal place

🔒 Security Changes

• Add CodeQL analysis @pgmitche (#5)