Fix/make region required for s3 bucket config

[mjmartinson]

Improvements

• Decrease response time when getting S3 presigned URLs by calling "get_bucket_region" at startup instead of when processing requests

Deployment changes

• In fence-config, the region field of S3_BUCKETS is now required: if not specified, Fence will print a warning and try to call GetBucketLocation. Fence will error at startup if that doesn't work.

[github-actions]

The style in this PR agrees with black. ✔️

This formatting comment was generated automatically by a script in uc-cdis/wool.

[coveralls]

Pull Request Test Coverage Report for Build 8413

• 18 of 23 (78.26%) changed or added relevant lines in 3 files are covered.
• 4 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.02%) to 69.478%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
fence/resources/aws/boto_manager.py	0	1	0.0%
fence/init.py	16	18	88.89%
fence/blueprints/data/indexd.py	2	4	50.0%

Files with Coverage Reduction	New Missed Lines	%
fence/blueprints/data/indexd.py	4	73.23%

Totals
Change from base Build 8394:	0.02%
Covered Lines:	5115
Relevant Lines:	7362

---

💛 - Coveralls

[lgtm-com]

This pull request introduces 1 alert when merging 5bb0862 into 8fefae0 - view on LGTM.com

new alerts:

• 1 for Unreachable code

[paulineribeyre]

good job! please remove your previous changes of raising a ValueError when the region is not specified

[lgtm-com]

This pull request introduces 2 alerts when merging 0639998 into 8fefae0 - view on LGTM.com

new alerts:

• 1 for Unreachable code
• 1 for Variable defined multiple times

[lgtm-com]

This pull request introduces 1 alert when merging 4aecd15 into 8fefae0 - view on LGTM.com

new alerts:

• 1 for Unreachable code

[lgtm-com]

This pull request introduces 1 alert when merging 84dbfa1 into 8fefae0 - view on LGTM.com

new alerts:

• 1 for Unreachable code