Refactoring of the script to update the manifests in-place where applicable

[Trenly]

Upon further review; This should also include a refactoring of the script to update the manifests in-place where applicable, instead of always creating new ones.

Logic Flow:

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During read previous flow
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If old singleton manifest exists
> Create new empty multi-manifest
> Copy existing fields from singleton into the appropriate multi-manifest file

If old multi-manifest exists
> Set new installer manifest equal to existing installer manifest
> Set new locale manifest equal to existing locale manifest
> Set new version manifest equal to old locale manifest

If no manifests exist
> Create new empty manifests

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During data entry flow
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For any new required entries
> Set the appropriate Manifest['Key'] value directly instead of using script variables

For any optional values
> If the value entered is null or empty, do not update the field
> If the value entered is not null and is valid, update the value in place

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During file creation flow
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Directly use the new manifests which were updated in-place 
Re-Sort the keys to ensure accuracy

Originally posted by @Trenly in #30 (comment)