Add quota usage as part of Prometheus metrics

[harshavardhana]

Description

Add quota usage as part of Prometheus metrics

Motivation and Context

Bonus: pass caller context when needed to all
bucket metadata handling calls.

How to test this PR?

Enable quota and should see

~ curl -s https://localhost:9000/minio/v2/metrics/cluster |grep bucket_quota
# HELP minio_bucket_quota_total_bytes Total bucket quota size in bytes
# TYPE minio_bucket_quota_total_bytes gauge
minio_bucket_quota_total_bytes{bucket="testbucket",server="127.0.0.1:9000"} 1.073741824e+09

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Optimization (provides speedup with no functional changes)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• Fixes a regression (If yes, please add commit-id or PR # here)
• Documentation updated
• Unit tests added/updated

[kannappanr]

LGTM

[minio-trusted]

Mint Automation

Test	Result
mint-large-bucket.sh	✔️
mint-fs.sh	✔️
mint-gateway-s3.sh	✔️
mint-erasure.sh	✔️
mint-dist-erasure.sh	✔️
mint-gateway-nas.sh	✔️
mint-compress-encrypt-dist-erasure.sh	✔️
mint-pools.sh	✔️
Deleting image on docker hub
{"detail": "Not found"}Deleting image locally