rc: register encryption+decryption key variables
rc: register encryption+decryption key variables

Resource configuration mappings now recognize keys
+ encryption-key
+ decryption-key

```shell
$ cat .driverc
hidden=true
encryption-password=bonjour
decryption-password=bonjour
$ drive push test.mp4 # Should be encrypted at rest
$ drive pull --piped test.mp4 > outf && diff outf test.mp4 # Should be decrypted properly
```

Fixes https://github.com/odeke-em/drive/issues/683.

sselph/drive,odeke-em/drive,Dedsec01/drive,odeke-em/drive,gdm85/drive,gdm85/drive,sselph/drive,gccpacman/drive,gccpacman/drive,Dedsec01/drive