45 restructuring package into src structure

[SiebeLeDe]

• Lower case tcutility package following the python guidelines: packages should be all lower-case and preferably one word
• Added a src structure by moving the "TCutility" package to "src/tcutility"
• References in the docs and tests have been updated and pass the workflow tests
• Added (missing) dependencies in the pyproject.toml such as docx and htmldocx

Closes #45
Closes #2

[YHordijk]

Ziet er allemaal netjes uit! Ik denk dat dit de v0.7.0 moet worden.

[SiebeLeDe]

Prima, dan zal ik dit mergen