Move yaml files to top directory

[yashi]

Currently, we have the following directories in this repo:

• etc
• py
• scripts
• xsd

etc/ contains many template files that are necessary for our YAML instance to work correctly.

py/create_xtce.py is the main script for converting YAML files to MDB definition files. This script also has the potential to be a generic YAML-to-MDB converter.

scripts/inst_cfg_mdb.sh is essentially an install script that users run and then can forget about.

xsd/xtce-v1.2.xsd is an XSD file for XTCE and used only by a GitHub workflow.

Our primary data files for the MDB are currently located under py/tctm, which makes them hard to find.

Consider moving py/tctm to a higher level in the directory structure so that our primary data is easier for users to discover.