Generate and commit later ngrams in insertMasterDocs

This commit refactors the flow code to generate the ngrams for
the master docs separately, and then it "commits" them later after such
docs have been associated with a `Node`.
4 jobs for adinapoli/issue-473 in 49 minutes and 41 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Cabal
passed #18313
cabal

00:23:22

 
  Stack
passed #18314
stack

00:04:16

 
  Bench
manual #18315
allowed to fail manual
bench
 
  Test
failed #18316
test

00:22:02

 
Name Stage Failure
failed
test Test
Test suite garg-test-hspec: FAIL
Test suite logged to:
/builds/gargantext/haskell-gargantext/dist-newstyle/build/x86_64-linux/ghc-9.6.6/gargantext-0.0.7.4.7/t/garg-test-hspec/opt/test/gargantext-0.0.7.4.7-garg-test-hspec.log
0 of 1 test suites (0 of 1 test cases) passed.
Error: [Cabal-7125]
Tests failed for test:garg-test-hspec from gargantext-0.0.7.4.7.

Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1