Inproved azure:// error handling and message responses

[caronc]

Description

Related issue (if applicable): #1478

Just trying to reproduce end user problem and cleaning up minor issues I find as I go.

Checklist

• Documentation ticket created (if applicable):** apprise-docs/##
• The change is tested and works locally.
• No commented-out code in this PR.
• No lint errors (use tox -e lint and optionally tox -e format).
• Test coverage added or updated (use tox -e minimal).

Testing

Anyone can help test as follows:

# Create a virtual environment
python3 -m venv apprise

# Change into our new directory
cd apprise

# Activate our virtual environment
source bin/activate

# Install the branch
pip install git+https://github.com/caronc/apprise.git@1478-azure-bulletproofing

# If you have cloned the branch and have tox available to you:
tox -e apprise -- -t "Test Title" -b "Test Message" \
  azure://credentials/

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (d503bcd) to head (d56b50f).

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #1499   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          180       180           
  Lines        23751     23755    +4     
  Branches      3856      3857    +1     
=========================================
+ Hits         23751     23755    +4     

Files with missing lines	Coverage Δ
apprise/plugins/office365.py	100.00% <100.00%> (ø)

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