Add types to compat module

[florimondmanca]

What does this PR do?

Add types to compat.py module in the SNMP package.

Motivation

Road to type checking!

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

[florimondmanca]

Note: mypy complains with "function overload must have same signature", so we can't add types for this until base total_time_to_temporal_percent gets types. Hence # type: ignore.

[codecov]

Codecov Report

Merging #6029 into master will increase coverage by 6.49%.
The diff coverage is 80.00%.

Impacted Files	Coverage Δ
snmp/datadog_checks/snmp/compat.py	80.00% <80.00%> (ø)
envoy/datadog_checks/envoy/__init__.py
dotnetclr/datadog_checks/dotnetclr/dotnetclr.py
...ystem_core/datadog_checks/system_core/__about__.py
gitlab/tests/common.py
postfix/tests/test_unit.py
gitlab/datadog_checks/gitlab/gitlab.py
consul/tests/test_integration.py
mesos_master/tests/test_integration_e2e.py
activemq/datadog_checks/activemq/__init__.py
... and 871 more