[encointer] introduce swap options for businesses through democracy

[brenzi]

This introduces new functionality for Encointer communities:

• democracy proposals can grant swap options to businesses for them to swap community currency for KSM from the community treasury. relevant pallet changes: swap_native options proposals encointer/pallets#411

Motivation

In order for community treasuries holding KSM to act as a reserve for community currencies, we need to enable some form of swap functionality. This functionality, however, needs to be permissioned, as we can't allow everyone to "exit" the demurrage-bearing community currency as this would undermine the community currency and deplete the treasury for no good.
Businesses making real turnover in community currency, however, should have an option to reduce their exposure. Otherwise, the most popular businesses will be punished by bearing the greatest risk by accumulating community currency before economic circles can be closed (which will eventually allow them to spend their community currency on goods and services they need).
The best available source of information which businesses add real value to the community is the community members. Therefore, we let the community vote on swap allowances for businesses using Encointer's personhood-based democracy process.

[brenzi]

/merge

[fellowship-merge-bot]

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