Add support for other systemic aliases specified in CLDR root.xml

[akx]

Overview Description

#892 was caused by us not reading <alias>es at all.

#1075 encodes the "hey, you can use short if you can't find these time deltas" logic from root.xml into code, which fixes that issue. There are other interesting <alias>es in root.xml we should support:

• dates.fields.field
• numbers.decimalFormats.decimalFormatLength
• numbers.scientificFormats
• numbers.percentFormats
• numbers.currencyFormats (especially that "if accounting isn't specified, use standard")
• Units (lots of them have name fallback aliases)
• List patterns (Support list format fallbacks #1099)

It looks like (thankfully) there are no <alias>es specified in specific locale files, and I don't think we need to support that.