regression: allow monitor to not require to specify the board if the port cannot be identified.

[cmaglie]

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• configuration.schema.json updated if new parameters are added.

What kind of change does this PR introduce?

If a port cannot be identified (i.e. can not be associated with a board) the current version of the CLI requires to specify a board with the -b flag. Previously this wasn't necessary and the monitor would sometimes fail to work because it may require special dtr / rts settings.

This PR now reverts the old behavior that is more convenient but also adds a warning to the user when the board can not be identified and the default settings may not work as expected.

What is the current behavior?

$ arduino-cli board list
Port       Protocol Type        Board Name FQBN Core
/dev/ttyS4 serial   Serial Port Unknown

$ arduino-cli monitor -p /dev/ttyS4
Please specify an FQBN. The board on port /dev/ttyS4 with protocol serial can't be identified
$ arduino-cli monitor -p /dev/ttyS4 -b esp32:esp32:esp32
Connecting to /dev/ttyS4. Press CTRL-C to exit.
^C

What is the new behavior?

$ arduino-cli board list
Port       Protocol Type        Board Name FQBN Core
/dev/ttyS4 serial   Serial Port Unknown

$ arduino-cli monitor -p /dev/ttyS4
Using generic monitor configuration.
WARNING: Your board may require different settings to work!

Monitor port settings:
  baudrate=9600
  bits=8
  dtr=on
  parity=none
  rts=on
  stop_bits=1

Connecting to /dev/ttyS4. Press CTRL-C to exit.
^C
$ arduino-cli monitor -p /dev/ttyS4 -b esp32:esp32:esp32
Using default monitor configuration for board: esp32:esp32:esp32
Monitor port settings:
  baudrate=9600
  bits=8
  dtr=off            <-- notice the esp32 requires DTR=off
  parity=none
  rts=off            <-- and also RTS=off
  stop_bits=1

Connecting to /dev/ttyS4. Press CTRL-C to exit.
^C

Does this PR introduce a breaking change, and is titled accordingly?

No

Other information

Fix #2638

[codecov]

Codecov Report

Attention: Patch coverage is 47.61905% with 22 lines in your changes missing coverage. Please review.

Project coverage is 70.23%. Comparing base (7d00b5b) to head (ca0101f).

Files	Patch %	Lines
internal/cli/monitor/monitor.go	52.94%	16 Missing ⚠️
internal/cli/arguments/port.go	33.33%	4 Missing ⚠️
internal/cli/arguments/fqbn.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2647      +/-   ##
==========================================
- Coverage   70.26%   70.23%   -0.03%     
==========================================
  Files         222      222              
  Lines       21338    21347       +9     
==========================================
  Hits        14993    14993              
- Misses       5165     5175      +10     
+ Partials     1180     1179       -1     

Flag	Coverage Δ
unit	70.23% <47.61%> (-0.03%)	⬇️

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