feat: Improve merge performances

It appears @fastify/deepmerge is faster than merge from lodash.
To measure performances, we first query 1000 docs. Then, we mutate each
doc, and make the query again.
We measure the whole `extractAndMergeDocument` function.

Before: 1626ms
After: 278ms

Author: paultranvan

packages/cozy-client/package.json

@@ -15,6 +15,7 @@
   },
   "dependencies": {
     "@cozy/minilog": "1.0.0",
+    "@fastify/deepmerge": "^2.0.2",
     "@types/jest": "^26.0.20",
     "@types/lodash": "^4.14.170",
     "btoa": "^1.2.1",

packages/cozy-client/src/store/documents.js

@@ -1,8 +1,8 @@
 import get from 'lodash/get'
 import omit from 'lodash/omit'
-import merge from 'lodash/merge'
-import logger from '../logger'
 import fastEqual from 'fast-deep-equal'
+import deepmerge from '@fastify/deepmerge'
+import logger from '../logger'
 import { isReceivingData } from './queries'
 import { MutationTypes } from '../queries/dsl'
 import { isReceivingMutationResult } from './mutations'
@@ -221,6 +221,7 @@ export const extractAndMergeDocument = (newData, updatedStateWithIncluded) => {
   }
 
   let haveDocumentsChanged = false
+  const deeppmerge = deepmerge()
 
   newDocsMap.forEach((newDoc, key) => {
     const id = key
@@ -235,7 +236,8 @@ export const extractAndMergeDocument = (newData, updatedStateWithIncluded) => {
       //  - some documents might change without a rev change: typically the thumbnails links
       //    in io.cozy.files, and the io.cozy.settings.instance doc, with additional
       //    fields added by the stack
-      mergedState[doctype][id] = merge({}, mergedState[doctype][id], newDoc)
+      //  - some documents don't have any revision
+      mergedState[doctype][id] = deeppmerge(mergedState[doctype][id], newDoc)
       haveDocumentsChanged = true
     }
   })

yarn.lock

@@ -1235,6 +1235,11 @@
     minimatch "^3.0.4"
     strip-json-comments "^3.1.1"
 
+"@fastify/deepmerge@^2.0.2":
+  version "2.0.2"
+  resolved "https://registry.yarnpkg.com/@fastify/deepmerge/-/deepmerge-2.0.2.tgz#5dcbda2acb266e309b8a1ca92fa48b2125e65fc0"
+  integrity sha512-3wuLdX5iiiYeZWP6bQrjqhrcvBIf0NHbQH1Ur1WbHvoiuTYUEItgygea3zs8aHpiitn0lOB8gX20u1qO+FDm7Q==
+
 "@humanwhocodes/config-array@^0.9.2":
   version "0.9.5"
   resolved "https://registry.yarnpkg.com/@humanwhocodes/config-array/-/config-array-0.9.5.tgz#2cbaf9a89460da24b5ca6531b8bbfc23e1df50c7"