Supported/unsupported coins for swap: brc20-db20

[teebszet]

Have an issue to do with which coins we allow swaps from.

we are currently filtering coins list to swap like this:

const acceptableCoinList =
      coinsList?.filter((c) => alexSDK.getCurrencyFrom(c.principal) != null) ?? [];

in the case of brc20-db20, this passes:

alexSDK.getCurrencyFrom("SP3K8BC0PPEVCV7NZ6QSRWPQ2JE9E5B6N3PA0KBR9.brc20-db20")
// brc20-db20

but if you try to run getFee or getRoute using "brc20-db20", you will get a ClarityError thrown:

decoders.js:74 Uncaught (in promise) Error: ClarityError: 2001
    at defaultErrorDecoder (decoders.js:74:1)
    at Object.decode (decoders.js:84:1)
    at _callee2$ (alex-sdk.esm.js:4018:1)
    at tryCatch (alex-sdk.esm.js:65:1)
    at Generator.<anonymous> (alex-sdk.esm.js:146:1)
    at Generator.next (alex-sdk.esm.js:90:1)
    at asyncGeneratorStep (alex-sdk.esm.js:327:1)
    at _next (alex-sdk.esm.js:346:1)

[fiftyeightandeight]

@zhigang1992 @bolasblack this feature (of getting the list of supported tokens) was requested by others too. Think something we want to implement either as an API endpoint or as part of SDK?
Also, we don't have AMM on brc20-db20, so this shouldn't be included (though we will add one pretty soon).