Added gRPC debugger

[cmaglie]

• Please check if the PR fulfills these requirements

• The PR has no duplicates (please search among the Pull Requests before creating one)
• The PR follows our contributing guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• UPGRADING.md has been updated with a migration guide (for breaking changes)

• What kind of change does this PR introduce?

This change allows the CLI to output all the gRPC calls including their payload (both request and responses) so they can be inspected. This may turn useful to debug gRPC API issues.

To enable the debugging output just run the daemon as usual with the flag:

      --debug                  Enable debug logging of gRPC calls

If you're interested only in some particular gRPC calls you can filter them using

      --debug-filter strings   Display only the provided gRPC calls

Example:

$ arduino-cli daemon --debug --debug-filter Create,SetValue,UpdateIndex
CALLED: /cc.arduino.cli.settings.v1.SettingsService/SetValue
|  REQ:  {
|    "key": "directories",
|    "json_data": "{\"data\": \"/tmp/arduino-rpc-client774405799\", \"downloads\": \"/tmp/arduino-rpc-client774405799/staging\", \"user\": \"/tmp/arduino-rpc-client774405799/sketchbook\"}"
|  }
|  RESP: {}

CALLED: /cc.arduino.cli.commands.v1.ArduinoCoreService/Create
|  REQ:  {}
|  RESP: {
|    "instance": {
|      "id": 1
|    }
|  }

CALLED: /cc.arduino.cli.settings.v1.SettingsService/SetValue
|  REQ:  {
|    "key": "network.proxy",
|    "json_data": "\"http://localhost:3128\""
|  }
|  RESP: {}

CALLED: /cc.arduino.cli.commands.v1.ArduinoCoreService/UpdateIndex STREAM_RESP
|  REQ:  {
|    "instance": {
|      "id": 1
|    }
|  }
|  ERROR:  rpc error: code = Internal desc = Error downloading index 'https://downloads.arduino.cc/packages/package_index.json': Get "https://downloads.arduino.cc/packages/package_index.json": proxyconnect tcp: dial tcp 127.0.0.1:3128: connect: connection refused

• Does this PR introduce a breaking change, and is titled accordingly?
  No