Feature Request: Programmatically create Bitcoin Stateless SPV Proofs without running a bcoin full node

[GandalfTheBrown]

Hi! It would be really helpful to have library functions that query one of the block explorers and parse the transaction data to generate SPV proofs in the format discussed in the SPV Proof CLI readme (copied below) without having to run a bcoin full node.

{
"version": "01000000",
"vin": "0168fe12339c9eb3ceaf21899b775a53dc10901f88f57ba7b360bbd285fe1b8731000000006a47304402206f33a57c88e473a26eca617c21aa9545101b18df83b127bc485bf0fea1a831b702204d56bc0e39fa14ff254d0677f46c3f7f26f6dea8e6a9c5ba90aace3c8476f1d401210396dd84815a4f121bf29b882c283ec1cd8b5bfa92773008a79cb44d981821a399ffffffff",
"vout": "0230182b00000000001976a91452ada19e1305964e80a1a1cbbafea97f6b632fae88aca7ec3703000000001976a914f9da3787e63ad9261517a6d4d9dabd2cf40fb80988ac",
"locktime": "00000000",
"tx_id": "fff0d18db9f52e6bff445c26cb8bb9658882c8045997a74be26003225713e762",
"tx_id_le": "62e71357220360e24ba7975904c8828865b98bcb265c44ff6b2ef5b98dd1f0ff",
"index": 6,
"confirming_header": {
"raw": "00e0002074859a363c5a885b262722d5c5c5cd912e2cd1a53d0c0c000000000000000000a0c7ea544dcc99af8af5415d4293856da7c07f9f1a3b145d2498b39bf5fa5e36fbd1d45dd1201617d64b8b4c",
"hash": "00000000000000000003e7124509796d4f15ef47fedc71c79cea60d1ff503410",
"hash_le": "103450ffd160ea9cc771dcfe47ef154f6d79094512e703000000000000000000",
"height": 604596,
"prevhash": "0000000000000000000c0c3da5d12c2e91cdc5c5d52227265b885a3c369a8574",
"prevhash_le": "74859a363c5a885b262722d5c5c5cd912e2cd1a53d0c0c000000000000000000",
"merkle_root": "365efaf59bb398245d143b1a9f7fc0a76d8593425d41f58aaf99cc4d54eac7a0",
"merkle_root_le": "a0c7ea544dcc99af8af5415d4293856da7c07f9f1a3b145d2498b39bf5fa5e36"
},
"intermediate_nodes": "c7ca43c16c6a587c3554d45a1c0d56e801ef2dc929fae3cc95bb604b3f566de1f6e9750121695b84989ba819f6cea180315f8a3ae71d644f1bb90379577dbc6d7167faee2d76d172fcec41469346d3d731a901fa86e71528a8569a414ef42ed5585623d28015eb91eb1dda03615196918e49e5f1ff0ef22974..."
}

[prestwich]

This should be relatively easy to put together using the blockstream esplora api (docs here)

@GandalfTheBrown note that recently the *_le fields were dropped, and all fields were changed to be LE by default