feat!: accept pre-configured import components as options instead of options for components (#283)

The existing importer takes one big options object that contains options for every subsystem.  This leads to situations where different components use the same option keys - for example both the rabin and fixed-size chunkers use the `maxChunkSize` key.

This PR reduces the number of options by accepting preconfigured instances of internal components - e.g. instead of passing `'"rabin"` for the chunker argument, you pass an instance of the rabin chunker instead.  This greatly simplifies the config and also allows a simple way for users to pass custom chunkers in.  The same thing applies to file layouts, dag builders etc.

Before:

```js
import { importer } from 'ipfs-unixfs-importer'

for await (const result of importer(stream, blockstore, {
  chunker: 'rabin',
  avgChunkSize: 512000,
  strategy: 'trickle'
}) {
  // ...
}
```

After:

```js
import { importer } from 'ipfs-unixfs-importer'
import { rabin } from 'ipfs-unixfs-importer/chunkers'
import { trickle } from 'ipfs-unixfs-importer/layouts'

for await (const result of importer(stream, blockstore, {
  chunker: rabin({
    avgChunkSize: 512000
  }),
  layout: trickle()
}) {
  // ...
}
```

Other breaking changes:

- This module is now typescript
- CID 1 is now the default
- Raw leaves: true is now the default
- The `onlyHash` option has been removed - just pass a `MemoryBlockstore` or other blockstore implementation that doesn't store the blocks anywhere
- The `strategy` config key is now `layout` and accepts an instance of a file layout instead of a string
- The `chunker` config key now accepts an instance of a file chunker instead of a string

`importContent`, `importBytes` and `importByteStream` functions are also now exported along side `importer` to make dealing with simple imports that only import one thing easier.

```js
import { importContent, importBytes, importByteStream } from 'ipfs-unixfs-importer'

// import single file/directory
const result = await importContent({
  path: 'foo.txt',
  content: Uint8Array.from([0, 1, 2, 3, 4])
}, blockstore, options)

// import single buffer
const result = await importBytes(Uint8Array.from([0, 1, 2, 3, 4]), blockstore, options)

// import single byte stream
const result = await importByteStream(fs.createReadStream('./foo.txt'), blockstore, options)
```

BREAKING CHANGE: The options object now accepts preconfigured instances of chunkers and file layouts - these can be imported from this module - see #283 for more

Author: achingbrain

Diff for: .gitignore

@@ -6,3 +6,4 @@ dist
 node_modules
 package-lock.json
 yarn.lock
+.vscode

Diff for: package.json

@@ -29,12 +29,13 @@
     "clean": "aegir run clean",
     "build": "aegir run build",
     "lint": "aegir run lint",
+    "generate": "aegir run generate",
     "docs": "NODE_OPTIONS=--max_old_space_size=4096 aegir docs",
     "docs:no-publish": "npm run docs -- --publish false",
     "dep-check": "aegir run dep-check",
     "release": "npm run docs:no-publish && aegir run release && npm run docs"
   },
-  "dependencies": {
+  "devDependencies": {
     "aegir": "^38.1.2"
   },
   "workspaces": [

Diff for: packages/ipfs-unixfs-exporter/package.json

@@ -20,22 +20,6 @@
   },
   "type": "module",
   "types": "./dist/src/index.d.ts",
-  "typesVersions": {
-    "*": {
-      "*": [
-        "*",
-        "dist/*",
-        "dist/src/*",
-        "dist/src/*/index"
-      ],
-      "src/*": [
-        "*",
-        "dist/*",
-        "dist/src/*",
-        "dist/src/*/index"
-      ]
-    }
-  },
   "files": [
     "src",
     "dist",
@@ -45,7 +29,7 @@
   "exports": {
     ".": {
       "types": "./dist/src/index.d.ts",
-      "import": "./src/index.js"
+      "import": "./dist/src/index.js"
     }
   },
   "eslintConfig": {
@@ -183,6 +167,6 @@
     "fs": false
   },
   "typedoc": {
-    "entryPoint": "./src/index.js"
+    "entryPoint": "./src/index.ts"
   }
 }