🐛 WriteTo truncates output file

[pleonex]

DataStream.WriteTo now truncates the output file. Before if the file existed, it was opening and overwriting data. This could have caused unexpected results as the output file may have not contained exactly the same content as the source stream.

Quality check list

• Related code has been tested automatically or manually
• Related documentation is updated
• I acknowledge I have read and filled this checklist and accept the
  developer certificate of origin

Acceptance criteria

• WriteTo truncates the file if exists

Follow-up work

none

Example

API doesn't change.