[data.fieldFormats] Remove aggs format decorator from fieldFormats.deserialize()

[lukeelmers]

As part of the preparation for making aggs available on the server, we extracted the aggs-specific logic from fieldFormats.deserialize and consolidated all of it into a single utility which decorates getFieldFormat with some special agg-specific formatter types:

kibana/src/plugins/data/public/field_formats/utils/deserialize.ts

Lines 55 to 56 in 16eaf82

	// decorate getFormat to handle custom types created by aggs
	const getFieldFormat = getFormatWithAggs(getFormat);

While this created a clearer separation of concerns, it still feels wrong to have field formats depending on aggs in this way.

So why can't aggs just be added to the registry like other formatters? This would be ideal as they wouldn't need special treatment by the field formats service. Currently there are two reasons we can't do this:

1. These formatters shouldn't show up in the field formats UI as they are only meant to be applied to fields for a specific aggregation type.
2. These formatters need to access other formatters in the registry, as they are decorating the existing formatters attached to the aggregation's field param with some additional functionality.

After some discussion with @stacey-gammon around whether the enhancements pattern could solve this problem, we agreed it is probably overkill for this particular scenario.

With that in mind, I'd propose taking the following steps to resolve this:

• Add a flag to FieldFormat that allows you to specify a format as hidden. The idea is that formats with hidden: true would not be surfaced in the UI. This could be achieved a number of ways, but perhaps the most simple way is to make it so that these formats are only available in the registry if you get them by ID (e.g. getType('some_hidden_format')), but they would not be available when you are getting collections of formats (e.g. getFieldByType('number')).
• Provide getType to every registered FieldFormat. This way any formatter in the registry could look up other formatters by ID at runtime, which opens up the possibility of new formatters enhancing/decorating existing ones. This could probably be provided via the fieldFormatMetaParamsDecorator.
• Register each of the existing custom agg formatters. This includes range, date_range, ip_range, and terms. These formats would be set to hidden: true and use the injected getType to access other formats at runtime.
• Remove the static FieldFormat.from() method. This is only used internally & by the aggs formatters. If the agg formatters exist in the registry, there is no longer a need for this method to be exposed publicly.
• Remove fieldFormats.deserialize dependency on aggs.

[elasticmachine]

Pinging @elastic/kibana-app-arch (Team:AppArch)