Basic language - read statement broken in grammar

In the Basic grammar, the [READ statement](https://github.com/vmssoftware/vms-ide/blob/c6d7cb4842a6aa3e14a70960fefa0818bf435afd/src/vms_basic/parser/BasicParser.g4#L1212C1-L1212C14) is not included in the [statement definition](https://github.com/vmssoftware/vms-ide/blob/c6d7cb4842a6aa3e14a70960fefa0818bf435afd/src/vms_basic/parser/BasicParser.g4#L788C1-L788C10), or referenced anywhere else.