feat: Add truncate option to flush command

[BinDruid]

Fixes #680
Passing --truncate to flush command executes a truncate SQL statement, instead of deleting log records.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.47%. Comparing base (5289482) to head (9b3eb2e).
Report is 26 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #681      +/-   ##
==========================================
+ Coverage   95.21%   95.47%   +0.25%     
==========================================
  Files          31       32       +1     
  Lines        1025     1083      +58     
==========================================
+ Hits          976     1034      +58     
  Misses         49       49              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[hramezani]

Thanks @BinDruid for this PR. I left some comments. Please address the coverage as well.
Then we are good to merge it.

[BinDruid]

@hramezani
I refactored the TruncateQuery class and added another test case to cover unsupported databases.

[hramezani]

Thanks @BinDruid for the update.

Please add a change log entry in CHANGELOG.md.

Sorry, I forgot to mention it before.

[BinDruid]

@hramezani Thanks for the heads up!
I have updated change log to include info about truncate option addition.

[hramezani]

Thanks @BinDruid