[breaking] Fix board attach CLI command, and remove gRPC API (#1930)

* Remove board attach cli interface

* Move tr function in separate file

* Remove BoardAttach gRPC interface command

* Remove BoardAttach calls from client_example

* go mod tidy

* Update board CLI command help text

Co-authored-by: Cristian Maglie <c.maglie@bug.st>

* Update dependency license metadata cache

* Re-Implementation of 'board attach' command

* Fixed comment indentation (gofmt)

* Update UPGRADING.md

* Added 'default_fqbn' and 'default_port' fields to sketch.yaml

* Added functions to load and save sketch project files

* Use sketch project file to determine default fqbn and port

* Implement 'attach board' using sketch project file

* Remove support for sketch.json

* Updated documentation

* Do not fully rewrite sketch.yaml when a key is automatically updated

* Fixed 'board attach' command output

* Do not write empty entries in sketch.yaml

* Apply suggestions from code review

Co-authored-by: per1234 <accounts@perglass.com>

* Update docs/UPGRADING.md

Co-authored-by: per1234 <accounts@perglass.com>

* Other suggestions from code review

* Updated UPGRADING.md

This change is going into 0.30.0

Co-authored-by: Cristian Maglie <c.maglie@bug.st>
Co-authored-by: per1234 <accounts@perglass.com>
Co-authored-by: Cristian Maglie <c.maglie@arduino.cc>