Move env file to parent directory to avoid conflict with config provider

[farshidtz]

Testing instructions

Reproduce the error

Install device virtual (edge) and connect the config provider.
Set a snap option (example: snap set edgex-device-virtual config.writable-loglevel=DEBUG)
Look for expected error: could not process config options: failed to remove env file: unlinkat /var/snap/edgex-device-mqtt/2762/config/device-mqtt/res/device-virtual.env: read-only file system

Test

Build from edgexfoundry/device-virtual-go#354
Connect the config provider.

Use:

$ snap set edgex-device-virtual config.writable-loglevel=DEBUG
$ cat /var/snap/edgex-device-virtual/current/config/device-virtual/overrides.env 
# System-generated list of environment variables from snap options
WRITABLE_LOGLEVEL="DEBUG"

[MonicaisHer]

I have installed the device virtual build with the PR's snap hook and connected it to the config provider. However, the files from the config provider have not been copied to the device-virtual:

$ snap install ./edgex-device-virtual_3.0.0-dev.21_amd64.snap --dangerous
$ tree /var/snap/edgex-device-virtual/current
/var/snap/edgex-device-virtual/current
└── config
    └── device-virtual
        └── res
            ├── configuration.toml
            ├── devices
            │   └── devices.toml
            └── profiles
                ├── device.virtual.binary.yaml
                ├── device.virtual.bool.yaml
                ├── device.virtual.float.yaml
                ├── device.virtual.int.yaml
                └── device.virtual.uint.yaml

5 directories, 7 files

$ snap install edgex-config-provider-example --edge
$ sudo snap connect edgex-device-virtual:device-virtual-config edgex-config-provider-example:device-virtual-config
$ tree /var/snap/edgex-device-virtual/current
/var/snap/edgex-device-virtual/current
└── config
    └── device-virtual
        └── res
            ├── configuration.toml
            ├── devices
            │   └── devices.toml
            └── profiles
                ├── device.virtual.binary.yaml
                ├── device.virtual.bool.yaml
                ├── device.virtual.float.yaml
                ├── device.virtual.int.yaml
                └── device.virtual.uint.yaml

5 directories, 7 files

[farshidtz]

I have installed the device virtual build with the PR's snap hook and connected it to the config provider. However, the files from the config provider have not been copied to the device-virtual:

The mounted files are only visible to the snap. See https://github.com/canonical/edgex-config-provider#list-mounted-files