This PR introduces major changes to the plastics input data generation.

1. Several new calculation functions are introduced in order to get plastics production data which will replace the OECD plastics consumption data in remind-mfa. OECD estimates were based on economic modelling and using plastics production data from a single year and regional per capita consumption estimates of which the source was no longer accessible (see Ryberg et al. 10.1016/j.resconrec.2019.104459). Using plastics production data directly will therefore improve the data quality and in addition, allow for more recent data.
   There are three different type of plastics for which production data is obtained from the following sources:

• "Plastics": regional production data from PlasticsEurope, including thermoplastics and thermosets, excluding fibres and rubber
• "Rubber": regional production data from the International Rubber Study Group (IRSG)
• "Fibre": global fibre production data from TextileExchange, disaggregated to regions using Credence Research market data on monoethylene glycol as a proxy for PET fibre production which accounts for >85% of global fibre production.
  These plastic types will now be differentiated throughout the historical MFA in remind-mfa, which is why I added the dimension "type" to the production output.

2. To split the plastics types further into polymers and to allocate their use to sectors, a dataset from Gao & Cabrera (10.1016/j.resconrec.2025.108518) with plastics consumption by sector and polymer is used. Polymers are mapped onto the three plastics types and the share of each sector x polymer combination within each type is calculated. Note that there are some differences with regards to the sector and polymer categories of OECD (e.g. "Others" are now split into "Other thermoplastics" and "Other thermosets", "Fibres" are further differentiated etc.).

3. Plastics trade flow mappings are adjusted to match the new polymer and sector categories, and the new type dimension is added here as well.

4. HVC input ratio and carbon content source data and calculations are adjusted to match the new polymer and sector categories.

5. Minor other changes and improvements:

• Fix warnings in calcPlTrade and calcStTrade that were introduced since backcasting takes place within the aggregation function and years added there were not taken into account when checking the "years" parameter of the calcOutput call.
• All time-dependent parameters (trades, eol rates) in plastics were extrapolated to the most recent year of the plastics production data (2022), which is now set as the end_historic year in fullMFA.
• Mechanical recycling loss and yield as well as ZeroRates calc functions were simplified as they are essentially just a scalar.