RTC input files support

[arthurvd]

Describe the desired functionality
Model classes to parse, represent and serialize RTC input files.
See RTC input documentation on: https://content.oss.deltares.nl/delft3d/manuals/D-Real_Time_Control_User_Manual.pdf#appendix.C
Since RTC input is so extensive, the hope is that we can auto-generate these Pydantic classes based on the XSD files. See the preparatory investigation for this in issue #141.

Functional requirements

• input path is a directory/path, no filename.
• All input files should be autodetected if they are present in that input path, based on the filenames below.
• support for toplevel input files
  • rtcDataConfig.xml Time series definitions, interface definitions for file io,
  • rtcParameterConfig.xml Externalized parameters for modification in external
  • rtcRuntimeConfig.xml Definition of runtime relevant info: time step size,
  • rtcToolsConfig.xml

Future ideas
Not yet under this issue: the above will produce pretty technical classes that relate directly to the RTX xmls file elements. In the future a "convenience layer" could be defined on top of this, offering API functions for defining particular kinds of controllers, and all the file-elements being automatically created then.