Remove dependencies (#59)

Reduced the non-dev dependencies by changing `getSchemaId` to take the
genesis hash instead of an `ApiPromise`

Problem
=======

Keeping the Polkadot/api libraries in version sync is difficult and
issues arise with dependencies in typescript with the additional
requirement that `@frequency-chain/api-augment` versions align.

Solution
========
Removed the dependency need.

README.md

@@ -24,7 +24,7 @@ import { dsnp } from "@dsnp/frequency-schemas";
 import { ApiPromise } from "@polkadot/api";
 
 const api = ApiPromise.create(/* ... */);
-console.log(await dsnp.getSchemaId(api, "broadcast"));
+console.log(dsnp.getSchemaId("broadcast", "1.3", api.genesisHash.toString()));
 ```
 
 The API connection is used only to identify the chain by its genesis hash.
@@ -40,7 +40,7 @@ dsnp.setSchemaMapping(api.genesisHash.toString(), {
   // ...
 });
 
-console.log(await dsnp.getSchemaId(api, "broadcast")); // yields 67
+console.log(dsnp.getSchemaId("broadcast", "1.2", api.genesisHash.toString())); // yields 67
 ```
 
 ### With Parquet Writer

dsnp/index.ts

@@ -1,5 +1,3 @@
-import { ApiPromise } from "@polkadot/api";
-
 import type { Schema } from "avsc";
 import { DSNPParquetSchema } from "@dsnp/schemas/types/dsnp-parquet.js";
 import {
@@ -283,19 +281,14 @@ chainMapping["default"] = {
 };
 
 /**
- * Gets the schemaId from the Frequency instance configured for
- * apiPromise for the given DSNP type and version. If version is
- * unspecified, the latest version is returned. (You probably only
- * need version if you're migrating.)
+ * Gets the schemaId for for given DSNP type and version and genesis hash.
+ * If version is unspecified, the latest version is returned. (You probably
+ * only need version if you're migrating.)
+ * If genesis hash is unspecified, the mainnet genesis hash and schema
+ * numbers will be used.
  */
-export const getSchemaId = async (
-  apiPromise: Promise<ApiPromise>,
-  schemaName: SchemaName,
-  dsnpVersion?: DSNPVersion,
-): Promise<number> => {
-  const api = await apiPromise;
-  const genesisHash = api.genesisHash.toString();
-  let mapping = chainMapping[genesisHash];
+export const getSchemaId = (schemaName: SchemaName, dsnpVersion?: DSNPVersion, genesisHash?: string): number => {
+  let mapping = chainMapping[genesisHash || GENESIS_HASH_MAINNET];
   // If we don't recognize this chain, use default mapping
   if (!mapping) mapping = chainMapping["default"];
   const versions = mapping[schemaName];