[ATR-28536][ATR-28717][ATR-28782] Working towards a trigger EDM refactor and integrating R4 into the EDM (part B)

Follows from !68370 (merged)

cc @cantel, @okuprash, @wiedenma, @fwinkl

Here in part B, I aim to make the following changes

• Change the signature of getTriggerEDMList to require the config flags (but make it such that it doesn't crash if you supply None for some e.g. standalone test use cases). Update all clients.
• Introduce a new function, getRawTriggerEDMList which takes flags. Every user of the TriggerEDMRun3.TriggerHLTListRun3 should obtain this list via this function such that every client gets a consistent copy. Updated all clients. Flags can be None and the year can be specified explicitly instead, good for unit tests.
• Mark the private functions inside TriggerEDM with an initial underscore.
• Removed unused functions inside TriggerEDM.
• Move the addExtraCollectionsToEDMList function from the TriggerEDMRun3 file to the TriggerEDM file.
• Re-work the addExtraCollectionsToEDMList fn to extend its functionality to adding new targets as well as new Aux (and completely new items). Give it unit tests.
• Add a unit test to make sure that allowTruncation items are only at the end of the EDM list

To follow in the next part:

• Attempt to refactor addHLTNavigationToEDMList to be called consistently (hard...)
• Add caching to the getRawTriggerEDMList function.
• Make it harder to obtain TriggerEDMRun3.TriggerHLTListRun3 without going via getRawTriggerEDMList(flags, 3), maybe wrap this list in a simple class.
• Connect up the Run 4 EDM file