chore(papi): commit the sources behind the four polkadot-api packages (#15)

* chore(papi): commit the sources behind the four polkadot-api packages

papi-utils, bizinikiwi-bindings, metadata-builders and merkleize-metadata
held only dist/ builds, and no repository held their source. Every
source map in dist/ embeds the TypeScript it was compiled from; that is
now committed as src/ (59 files), and it matches upstream polkadot-api
(MIT) exactly once @polkadot-api/* imports are renamed:

  papi-utils           @polkadot-api/utils 0.2.0
  bizinikiwi-bindings  @polkadot-api/substrate-bindings 0.16.6
  metadata-builders    @polkadot-api/metadata-builders 0.13.0-0.13.2
  merkleize-metadata   @polkadot-api/merkleize-metadata 1.1.21-1.1.23

scripts/check-papi-sources.mjs, run in the lint job, fails unless the
source embedded in dist/ is exactly the committed src/. tsconfig.json
excludes these src/ trees; ESLint already skipped the packages. Each
README now states the upstream package and version.

* chore(papi): keep the upstream sources in upstream-src/

The pezkuwi-dev build treats any package with a src/ directory as its
own: it requires our license header on every file and builds it. These
are upstream files that must stay byte-identical to the source embedded
in dist/, so they live in upstream-src/ instead, which neither the build
nor the root tsconfig picks up.

packages/metadata-builders/upstream-src/with-cache.ts

@@ -0,0 +1,44 @@
+import { LookupEntry } from "./lookups"
+
+type FnWithStack<Other extends Array<any>, T> = (
+  input: LookupEntry,
+  cache: Map<number, T>,
+  stack: Set<number>,
+  ...rest: Other
+) => T
+
+export const withCache =
+  <Other extends Array<any>, T>(
+    fn: FnWithStack<Other, T>,
+    onEnterCircular: (
+      cacheGetter: () => T,
+      circular: LookupEntry,
+      ...rest: Other
+    ) => T,
+    onExitCircular: (
+      outter: T,
+      inner: T,
+      circular: LookupEntry,
+      ...rest: Other
+    ) => T,
+  ): FnWithStack<Other, T> =>
+  (input, cache, stack, ...rest) => {
+    const { id } = input
+    if (cache.has(id)) return cache.get(id)!
+
+    if (stack.has(id)) {
+      const res = onEnterCircular(() => cache.get(id)!, input, ...rest)
+      cache.set(id, res)
+      return res
+    }
+
+    stack.add(id)
+    let result = fn(input, cache, stack, ...rest)
+    stack.delete(id)
+
+    if (cache.has(id))
+      result = onExitCircular(result, cache.get(id)!, input, ...rest)
+
+    cache.set(id, result)
+    return result
+  }