getInterchain: perChain + chains options (default first anchor per chain); bump 1.5.0

transaction.getInterchain / block.getInterchain take an optional
{ perChain?, chains? } that maps to prime-node's ?perChain=&chains= params.
Default (no options) returns one anchor per chain. Shared buildInterchainQuery
helper + InterchainOptions type, exported; jest-tested.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@dragonchain-inc/prime-sdk",
-  "version": "1.4.0",
+  "version": "1.5.0",
   "description": "Official Dragonchain Prime SDK for Node.js and TypeScript",
   "main": "./dist/index.js",
   "module": "./dist/index.mjs",