feat: Add support for harness CI

[calvin-codecov]

Closes https://github.com/codecov/core-engineering/issues/71

• adds CI adapter for harness
• uses env variables from https://developer.harness.io/docs/continuous-integration/troubleshoot-ci/ci-env-var/
• uses CI_ prefixed environment variables variant if available and DRONE_ prefixed environment variables variant if not
• Note: DRONE variables overlap with the Drone CI Adapter as Harness CI is built on top so instead of using eturn os.getenv("DRONE") == "true" for the detect function, using HARNESS_BUILD_ID

Successful Harness CI pipeline build in QA

https://qa.harness.io/ng/account/px7xd_BFRCi-pfWPYXVjvw/all/orgs/default/projects/calvin/pipelines/Build_codecov_example_python_1782243281624/executions/8HZcFrciSWSswjbQ5OYGTA/pipeline?connectorRef=account.Github&repoName=codecov/example-python&branch=cy/harness_test&storeType=REMOTE

Older Successful Harness CI pipeline build

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
723	1	722	1

View the full list of 1 ❄️ flaky test(s)

api.temp.calculator.test_calculator::test_divide

Flake rate in main: 100.00% (Passed 0 times, Failed 296 times)

Stack Traces | 0.001s run time

def
                test_divide():
                > assert Calculator.divide(1, 2) == 0.5
                E assert 1.0 == 0.5
                E + where 1.0 = <function Calculator.divide at 0x104c9eb90>(1, 2)
                E + where <function Calculator.divide at 0x104c9eb90> = Calculator.divide
                .../temp/calculator/test_calculator.py:30: AssertionError