Improve test coverage for pipelines-common

[martyngigg]

Improve the test coverage for the pipelines-common package.

Output of pytest --cov=src tests/unit_tests at time of issue creation:

Name                                                                   Stmts   Miss  Cover
------------------------------------------------------------------------------------------
src/pipelines_common/__init__.py                                           0      0   100%
src/pipelines_common/cli.py                                               37     37     0%
src/pipelines_common/constants.py                                          1      1     0%
src/pipelines_common/dlt_destinations/__init__.py                          2      0   100%
src/pipelines_common/dlt_destinations/pyiceberg/__init__.py                0      0   100%
src/pipelines_common/dlt_destinations/pyiceberg/catalog.py                13      7    46%
src/pipelines_common/dlt_destinations/pyiceberg/configuration.py          50      9    82%
src/pipelines_common/dlt_destinations/pyiceberg/exceptions.py             18      8    56%
src/pipelines_common/dlt_destinations/pyiceberg/factory.py                27     15    44%
src/pipelines_common/dlt_destinations/pyiceberg/pyiceberg.py             179    125    30%
src/pipelines_common/dlt_destinations/pyiceberg/pyiceberg_adapter.py      82     41    50%
src/pipelines_common/dlt_destinations/pyiceberg/schema.py                 65     38    42%
src/pipelines_common/dlt_sources/__init__.py                               0      0   100%
src/pipelines_common/dlt_sources/m365/__init__.py                         25      0   100%
src/pipelines_common/dlt_sources/m365/helpers.py                          42      4    90%
src/pipelines_common/dlt_sources/m365/settings.py                          1      0   100%
src/pipelines_common/logging.py                                           16     16     0%
src/pipelines_common/pipeline.py                                           3      3     0%
------------------------------------------------------------------------------------------
TOTAL                                                                    561    304    46%

Note that this is unit test coverage but we also have the e2e_tests to more thoroughly test the pyiceberg destination. This should be factored in.