Add support for dump CLI extra parameters

[JoaRiski]

Add support for defining extra parameters to pass to the dump CLI tool, for
both the pg_dump and mysqldump

Resolves #22

[codecov]

Codecov Report

Merging #23 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #23   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          13     13           
  Lines         446    474   +28     
  Branches       91     97    +6     
=====================================
+ Hits          446    474   +28

Impacted Files	Coverage Δ
database_sanitizer/dump/postgres.py	100% <100%> (ø)	⬆️
database_sanitizer/dump/mysql.py	100% <100%> (ø)	⬆️
database_sanitizer/config.py	100% <100%> (ø)	⬆️

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[suutari-ai]

Why don't you just make --single-transaction a default parameter for MySQL? Then the support for custom parameters wouldn't be needed at all, right? (Would result in less code to maintain and less special cases to test)

[JoaRiski]

@suutari-ai there might be cases where you don't want to do that, e.g. with MyISAM engine based databases. Additionally I think this is more future proof in case there's other flags that might need to be set.

[JoaRiski]

Added the --single-transaction as a default in the configured extra parameters, which this still allows for it to be removed if the extra parameters are manually defined in the .sanitizerconfig file.

[suutari-ai]

Well, I guess it's good that this can be configured, after all. As long as the defaults are good too, as they are now.

Nice work! 👍