[Fix] read_acqknowledge now also imports duplicated channel names

[DerAndereJohannes]

Description

This PR aims at fixing the read_acqknowledge file which skipped duplicated channel names (e.g., Digital input channels)

Proposed Changes

I changed the read_acqknowledge in such a way where instead of iterating through the named_channels, it now iterates through the list of channels (by index) and add the channel.name to a counter. If there is a duplicate, the channel name now adds a number e.g., (1) to the end of the channel name if the channel has already been added.

Example difference

Before:

print(data.columns)
Index(['PPG, Y, PPGED-R', 'RSP, Y, RSPEC-R', 'EMG A, Y, EMG2-R',
       'SKT A, Y, SKT2-R', 'SKT B, X, SKT2-R', 'ECG, X, RSPEC-R',
       'EMG B, X, EMG2-R', 'EDA, X, PPGED-R', 'Digital input'],
      dtype='object')

After:

print(data.columns)
Index(['PPG, Y, PPGED-R', 'RSP, Y, RSPEC-R', 'EMG A, Y, EMG2-R',
       'SKT A, Y, SKT2-R', 'SKT B, X, SKT2-R', 'ECG, X, RSPEC-R',
       'EMG B, X, EMG2-R', 'EDA, X, PPGED-R', 'Digital input',
       'Digital input (1)', 'Digital input (2)', 'Digital input (3)',
       'Digital input (4)', 'Digital input (5)', 'Digital input (6)',
       'Digital input (7)'],
      dtype='object')

Checklist

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• I have read the CONTRIBUTING file.
• My PR is targeted at the dev branch (and not towards the master branch).
• I ran the CODE CHECKS on the files I added or modified and fixed the errors.
• I have added the newly added features to News.rst (if applicable)

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