Add FeaturesDroppedLoader to extract header value

[felixpalmer]

Description

Shortcut

• Story: https://app.shortcut.com/cartoteam/story/268367/header-reading-loader-mode-in-deck-gl
• Update loaders.gl to include header reading functionality
• Use custom loader to parse out header to avoid having to invoke custom fetch function

Type of change

• Refactor

Acceptance

I have struggled to link the C4R codebase to another project, and had to test by copying files across into a modified project. For full acceptance it would be good for someone with more experience working with C4R to try linking in this modified code into an existing app to verify the feature dropping behavior works as expected

[felixpalmer]

Related fix in Builder: https://github.com/CartoDB/cloud-native/pull/10499

[coveralls]

Pull Request Test Coverage Report for Build 3900835381

• 0 of 4 (0.0%) changed or added relevant lines in 2 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.2%) to 71.802%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/react-api/src/hooks/useTileFeatures.js	0	1	0.0%
packages/react-api/src/hooks/FeaturesDroppedLoader.js	0	3	0.0%

Files with Coverage Reduction	New Missed Lines	%
packages/react-api/src/hooks/useTileFeatures.js	1	27.94%

Totals
Change from base Build 3838259542:	0.2%
Covered Lines:	1878
Relevant Lines:	2428

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💛 - Coveralls

[VictorVelarde]

LGTM