Make role configuration step more explicit

[ChristineTChen]

What does this PR do?

This PR emphasizes the creation of custom role to monitor Snowflake with sql example.

• make role config option required because default ACCOUNTADMIN is removed.
• encourages users to use better security practices according to Snowflake
• Add example script for creating new user/role or just assigning permissions to sysadmin role
• clarify debug log for proxy

Motivation

Make note more obvious in configuration step.

Additional Notes

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have changelog/ and integration/ labels attached

[codecov]

Codecov Report

Merging #8092 (7f635c3) into master (d417e16) will increase coverage by 5.52%.
The diff coverage is 44.44%.

Impacted Files	Coverage Δ
snowflake/datadog_checks/snowflake/config.py	85.71% <33.33%> (-3.18%)	⬇️
snowflake/datadog_checks/snowflake/check.py	91.66% <50.00%> (-0.74%)	⬇️
eks_fargate/tests/test_eks_fargate.py
kube_proxy/datadog_checks/kube_proxy/__init__.py
ibm_db2/tests/test_integration.py
kyototycoon/tests/test_kyototycoon.py
prometheus/tests/conftest.py
hdfs_namenode/tests/conftest.py
ambari/tests/conftest.py
aerospike/tests/common.py
... and 898 more

[florimondmanca]

Agreed this is a better approach. Nice one!