[MODEL] Add scripts for Joint intent classification and slot labelling with BERT

[sxjscience]

Description

(Brief description on what this PR is about)

Checklist

Essentials

• PR's title starts with a category (e.g. [BUGFIX], [MODEL], [TUTORIAL], [FEATURE], [DOC], etc)
• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage
• Code is well-documented

Changes

• Intent classification and slot labelling tutorial

[codecov]

Codecov Report

❗ No coverage uploaded for pull request head (intent_slot@18d5890). Click here to learn what that means.
The diff coverage is n/a.

[codecov]

Codecov Report

Merging #817 into master will decrease coverage by 9.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #817      +/-   ##
==========================================
- Coverage    90.4%   81.39%   -9.02%     
==========================================
  Files          66       66              
  Lines        6348     6348              
==========================================
- Hits         5739     5167     -572     
- Misses        609     1181     +572

Impacted Files	Coverage Δ
src/gluonnlp/data/batchify/batchify.py	96.42% <100%> (ø)	⬆️
src/gluonnlp/model/train/cache.py	26.19% <0%> (-71.43%)	⬇️
src/gluonnlp/model/train/language_model.py	42.04% <0%> (-55.12%)	⬇️
src/gluonnlp/embedding/evaluation.py	41.8% <0%> (-54.1%)	⬇️
src/gluonnlp/data/batchify/language_model.py	44.03% <0%> (-52.3%)	⬇️
src/gluonnlp/model/translation.py	20.63% <0%> (-50.8%)	⬇️
src/gluonnlp/model/language_model.py	50.38% <0%> (-49.62%)	⬇️
src/gluonnlp/model/bert.py	70.28% <0%> (-28.99%)	⬇️
src/gluonnlp/data/translation.py	73.64% <0%> (-26.36%)	⬇️
src/gluonnlp/model/train/__init__.py	75% <0%> (-25%)	⬇️
... and 13 more

[mli]

Job PR-817/12 is complete.
Docs are uploaded to http://gluon-nlp-staging.s3-accelerate.dualstack.amazonaws.com/PR-817/12/index.html

[mli]

Job PR-817/13 is complete.
Docs are uploaded to http://gluon-nlp-staging.s3-accelerate.dualstack.amazonaws.com/PR-817/13/index.html

[mli]

Job PR-817/14 is complete.
Docs are uploaded to http://gluon-nlp-staging.s3-accelerate.dualstack.amazonaws.com/PR-817/14/index.html

[mli]

Job PR-817/15 is complete.
Docs are uploaded to http://gluon-nlp-staging.s3-accelerate.dualstack.amazonaws.com/PR-817/15/index.html

[mli]

Job PR-817/16 is complete.
Docs are uploaded to http://gluon-nlp-staging.s3-accelerate.dualstack.amazonaws.com/PR-817/16/index.html

[mli]

Job PR-817/17 is complete.
Docs are uploaded to http://gluon-nlp-staging.s3-accelerate.dualstack.amazonaws.com/PR-817/17/index.html

[mli]

Job PR-817/18 is complete.
Docs are uploaded to http://gluon-nlp-staging.s3-accelerate.dualstack.amazonaws.com/PR-817/18/index.html