[+] add params column to timetable.execution_log table, closes #739

[pashagolub]

Move task logging inside the actual functions. Now every set of parameters produce a separate entry in timetable.execution_log table. Simplify the return of task functions with just error.

[coveralls]

Pull Request Test Coverage Report for Build 21172607922

Details

• 64 of 66 (96.97%) changed or added relevant lines in 6 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 87.298%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/pgengine/transaction.go	23	24	95.83%
internal/scheduler/chain.go	13	14	92.86%

Files with Coverage Reduction	New Missed Lines	%
internal/scheduler/interval_chain.go	3	82.61%

Totals
Change from base Build 20375822215:	-0.1%
Covered Lines:	1725
Relevant Lines:	1976

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💛 - Coveralls