The plugin cannot connect to the Emulator when private key in file mode with cadence.customConfigPath not project root

[btspoony]

Instructions

Problem

https://discord.com/channels/613813861610684416/1169205586496331836/1169579486229041259
When I set the private key of emulator-account to key: { "type": "file", "location": "./emulator.key"}
the Cadence VSCode plugin cannot connect to the Emulator properly.
It must be changed to key: "{privatekey}" in order to let the plugin work correctly.
In the project settings, there is a .vscode/setting.json file, and cadence.customConfigPath is configured for flow.json instead of being in the root directory.

Steps to Reproduce

1. place the flow project in a subfolder instead of the root directory and set the cadence.customConfigPath
2. change the private key of emulator-account to key: { "type": "file", "location": "./emulator.key"}
3. create an emulator.key file including the private key
4. start emulator, can start normally..
5. the plugin will not be connnected.
6. change the key to key: "{privateKey}"
7. restart language service, the plugin will be working.

Acceptance Criteria

The plugin works well.

Context

https://discord.com/channels/613813861610684416/1169205586496331836/1169579486229041259

[jribbink]

This will no longer be an issue when the emulator connection is removed #466