fix: split s3 client into 3 separate clients

[fenos]

What kind of change does this PR introduce?

Bug Fix

What is the current behavior?

A single S3 client for all operations.

What is the new behavior?

Split the S3 client into 3 separate instances:

• Api calls
• Uploads
• Download

This allows for granular scaling and granular timeouts on different types of operations

[coveralls]

Pull Request Test Coverage Report for Build 17731614194

Details

• 106 of 117 (90.6%) changed or added relevant lines in 6 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.06%) to 76.037%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/storage/backend/index.ts	6	7	85.71%
src/http/plugins/signals.ts	13	15	86.67%
src/storage/backend/file.ts	2	4	50.0%
src/storage/backend/s3/adapter.ts	68	74	91.89%

Files with Coverage Reduction	New Missed Lines	%
src/http/plugins/signals.ts	1	92.98%
src/storage/backend/s3/adapter.ts	1	81.55%

Totals
Change from base Build 17552349119:	0.06%
Covered Lines:	20956
Relevant Lines:	27333

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💛 - Coveralls