Add core ID in outdated command output

[silvanocerza]

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?

Enhancences an existing command.

• What is the current behavior?

outdated command doesn't print the IDs of outdated platforms.

Core name                       Installed version New version
Arduino AVR Boards              1.8.2             1.8.3
Arduino Mbed OS Portenta Boards 2.4.0             2.4.1

• What is the new behavior?

outdated command now shows all outdated cores IDs.

Core name                       Core ID               Installed version New version
Arduino Mbed OS Portenta Boards arduino:mbed_portenta 2.4.0             2.4.1
Arduino AVR Boards              arduino:avr           1.8.2             1.8.3

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

Nope.

• Other information:

None.

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[ubidefeo]

Works as expected