Split encoding from writing in grib output

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 89.92%. Comparing base (4f7ad4d) to head (66f7521).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #409 +/- ## ======================================== Coverage 89.92% 89.92% ======================================== Files 120 120 Lines 7764 7764 Branches 675 675 ======================================== Hits 6982 6982 Misses 651 651 Partials 131 131 ```

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