Fixes incorrect 'selection' and 'expansion' behaviour

[DevAhamed]

When the sections have selection/expansion mode as single and adapter has mode as multiple, then incorrect mode is set for adapter. This is discussed in this issue #72. Same issue has been fixed in 2.x branch as well.

Failing test cases were added to accept and verify the issue was resolved.

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (3.x@c51adf4). Click here to learn what that means.
The diff coverage is 100%.

@@          Coverage Diff           @@
##             3.x      #74   +/-   ##
======================================
  Coverage       ?   76.74%           
======================================
  Files          ?       20           
  Lines          ?     1105           
  Branches       ?      169           
======================================
  Hits           ?      848           
  Misses         ?      158           
  Partials       ?       99

Impacted Files	Coverage Δ
...pter/src/main/java/mva3/adapter/NestedSection.java	77.25% <100%> (ø)

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