Option to merge blocks in serialized data

[oelbert]

Description
This PR adds an option to merge data into a single savepoint when the Fortran code has been horizontally blocked. Data is reshaped into nx by ny in order to fit directly into the correct quantity size.

How Has This Been Tested?
This code has been used to postprocess test data for pySHiELD development

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included

[FlorianDeconinck]

• Remove changed to gt4py and dace
• Run Lint

[fmalatino]

lgtm

[FlorianDeconinck]

This is the way

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