Add functionality to Rust compile tool to output Ledger-compatible registry data

[hdevalence]

For a Ledger app, we want to have a hardcoded asset registry with the following data:

• Asset ID (32-byte array)
• Symbol
• Decimals for Symbol
• Base denom string (TODO: check if this is needed, I think it might not be, and that could save space)

The Zondax team suggested a structure like

static const asset_info_t supported_assets[] = {    {{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,      0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F},     "NAM", "Namada", 6},    {{0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,      0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F},     "BTC", "Bitcoin", 8},    {{0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F,      0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B, 0x5C, 0x5D, 0x5E, 0x5F},     "ETH", "Ethereum", 18},};
typedef struct {
    uint8_t asset_id[ASSET_ID_LEN];
    const char symbol[40];
    // TODO: is this too much for a asset name?
    const char name[120];
    uint16_t decimals;
} asset_info_t;

The Rust tool in the repo that compiles the asset registry should be augmented so that it can also produce this data. That should be fairly straightforward since this is a subset of the data it already produces.

One thing that would be good to do is ensure that the list of assets is sorted by lexicographic byte order on the asset ID. This will allow C code that consumes the array to efficiently traverse even large asset lists, by performing a binary search on the asset IDs rather than having to do a linear scan.

cc @redshiftzero