Latvijas pasts parcel lockers and mail boxes

[markalex2209]

Added parcel lockers and mail boxes for Latvija Pasts.

Some points that might need addressing before merge:

• Both are placed into Parcel locker category. In theory mail boxes might better fit into a dedicated category for post related analysis (that would include existing post codes analysis), but I'm not sure on that.
• Mail boxes are simply selected with amenity=post_box without any regard to name/operator/brand under the assumption that only Latvija Pasts has mail boxes. This assumption might be incorrect, better local knowledge is require to evaluate.

Additionally, LatviaPostAnalysisData.LatviaPostItems contains all types of elements present on the map of Latvijas Pasts (categories listed here), but only mail boxes and parcel lockers are used for analysis. I don't know what to do with CircleK and the last one, but offices can be used for #31.

[HellMapGoesCoding]

I encountered the same web issue as with Venipak - fails with SSL on GitHub, doesn't respond on local. Works with headless browsing, but result it wrapped it in boilerplate HTML.