Tabular Parser: sub_sub_sections in row mode

We are getting deeper with this tool and this leads us relentlessly to some new feature request.

When using the row mode, some users have a bundle of columns that repeats along the row because they use a single repeated class multiple times in that row.

This is an example of table we may face (note that process step, date, user, location, are not repeated in the row):

Process step	date	user	location	Material	Sputtering	Density	Voltage	Material	Sputtering	Density	Voltage
1	01-01-22	john	Berlin	MgO	Y	2.3	4	TiO	Y	4.5	45
2	02-01-22	micha	Berlin	ZnO	Y	2.3	4	CS	Y	4.5	45

and this is how it should be parsed in the archive:

data:
  m_def: my_experiment
  process_steps: # this is the repeated section parsed currently by our table parser
    - date: 01-01-22
      user: john
      location: Berlin
      sputtered_materials:
        - name: MgO
          sputtering: Y
          density: 2.3
          voltage: 4
        - name: TiO
          sputtering: Y
          density: 4.5
          voltage: 45
    - date: 02-01-22
      user: micha
      location: Berlin
      sputtered_materials:
        - name: ZnO
          sputtering: Y
          density: 2.3
          voltage: 4
        - name: CS
          sputtering: Y
          density: 4.5
          voltage: 45

So each row gives rise to an instance of a repeated subsection, and each bundle of columns in the same row gives rise to an instance of a repeated sub_sub_section.

I can already implement a schema where I parse every column manually into a different instance but this carries a couple of drawbacks:

• I have to rename each column with a different name so I can use the tabular annotation as it is now
• I have to redundantly define a schema for each bundle that is essentially the same class
• I have to know a priori how many times that class is used in that row, but this is not always know and can even vary

I explained already this issue to @amgo