[bug]: clearer error with price oracle that does not support the asset requested

[ZZiigguurraatt]

I have a price oracle that is not configured for the asset that tapd is trying to get a quote for

In this case the price oracle responds with

error {
  message: "unsupported subject asset"
}

However, when I try to create an invoice, tapd responds with

peer 0295541b89d8f41745177da175a1e7d3968fb7ceea4ca3b755f98e92ba3ef9a823 rejected the quote, code: 0, error message: unknown reject error

tapd should include the "unsupported subject asset" message that the price oracle gave to it.

[jtobin]

Closing this one in favour of #1749, which subsumes it.

[ZZiigguurraatt]

Closing this one in favour of #1749, which subsumes it.

I think this is a different issue because in the case I've described above, the price oracle responded with a useful message, but tapd did not pass that useful information along to the user when the invoice creation process failed