Add check for USB ID when getting COM port

[ConorPKeegan]

Changes

• Add a function to get target USB IDs for all of the connected and mounted mbed devices by their target IDs
• Add a check for a different target ID and target USB ID when getting the COM port from target ID, and then get the COM port from the target USB ID

Fixes

• This pull request fixes get_mbed_com_port does not return feasible port for NUCLEO_F401RE #126

[ConorPKeegan]

@mazimkhan @adbridge @bridadan Can you please review this

[bridadan]

It looks like the target_id logic here is duplicated from the function discover_connected_mbeds. Do you think you could break out this logic into a separate function and use it in both functions?

[bridadan]

Thanks for looking at that @ConorPKeegan, changes look good to me.

[mazimkhan]

LGTM