fix: sink all records to file after stream closes

[GrayFlash]

closes #366

[mabdh]

@GrayFlash are we making append vs overwrite configurable by user?

[StewartJingga]

@GrayFlash When there is an existing file on overwrite mode, it will now remove the existing file on initialization.

What it means is, even before sinking process, if there is an issue on other plugins configuration, we would already remove the existing file.

Will that behaviour be expected? cc: @bsushmith @mabdh @ravisuhag

if not, one thing we could do it, we can sink the result to a temporary file, and once everything is done, we replace the existing file with the temp file.

[ravisuhag]

@StewartJingga I think that should be fine as the user has already taken the decision of overriding it. Extraction is happening post that decision.