fix some potential memory leaks (#10)

Co-authored-by: fredrik <fredrik@jotta.no>

Additional hardening and updates (#9)

* additional hardening

* check if time is zero the right way

* oleHelper replaces must with err returns

* CoUninitialize must run on the same thread that called CoInitializeEx

* add DefaultDefinition

* internal logic tests that do not require a real task scheduler connection

* error codes

* ole date is local

* renovate config:base to config:recommended

* recursively release subfolders to avoid memory leaks

* %v to %w

* release COM-objects earlier to avoid accumulating until the whole collection has been filled

* IntToDayOfMonth with bit shift

* added GetTasksInFolder

* replaced deprecated rickb777/date with rickb777/period

* readme

* error mappings

* fix TaskResult off-by-one bug

* better validation errors

* added some gotchas to the readme

* formatting

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Co-authored-by: fredrik <fredrik@jotta.no>