fix: clear tokens on logout

[rajarju]

aio logout was not clearing refresh_token

Description

• show confirmation messages on logout
• show confirmation message if already logged out

Related Issue

Fixes: #32

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[shazron]

build is failing, because of missing tests (or tests not changed).

[codecov]

Codecov Report

Merging #33 into master will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #33   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          115       120    +5     
  Branches        24        25    +1     
=========================================
+ Hits           115       120    +5     

Impacted Files	Coverage Δ
src/commands/auth/logout.js	100.00% <100.00%> (ø)

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[rajarju]

@shazron Please review the changes