Check commands for bugs and add tests

[starchypotatocode]

Commit 1: Remove dead code with unused lines, does not affect user-facing behaviour.
Commit 2: Add tests to command parsers.
Commit 3: Add final tests to commands.
Commit 4: Checkstyle.
Commit 5: Merge from master.
Commit 6: Checkstyle, again.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ	Complexity Δ
...hallpointer/address/model/session/SessionDate.java	100.00% <100.00%> (ø)	11.00 <0.00> (ø)
...r/address/storage/JsonSerializableHallPointer.java	93.75% <100.00%> (ø)	4.00 <0.00> (ø)

... and 3 files with indirect coverage changes