Enhance Airflow Plugin

[Future-Outlier]

Tracking issue

Fixes flyteorg/flyte#3936

Why are the changes needed?

• need to install the flyteidl package to ensure the airflow plugin works properly

What changes were proposed in this pull request?

• add flyteidl package in setup.py
• add type annotation for is_deferrable function

How was this patch tested?

pytest

Setup process

Screenshots

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Related PRs

#1725

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (949bc1b) 85.73% compared to head (4a33620) 85.73%.
Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2099      +/-   ##
==========================================
- Coverage   85.73%   85.73%   -0.01%     
==========================================
  Files         313      313              
  Lines       23448    23455       +7     
  Branches     3514     3516       +2     
==========================================
+ Hits        20103    20108       +5     
- Misses       2735     2737       +2     
  Partials      610      610              

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