Install redis extra in AWS Lambda feature server & add hiredis depend…

[tsotnet]

…ency

What this PR does / why we need it:

1. Re-introduce installing redis extra in AWS lambda-based feature server. This makes it possible to use public Redis endpoints with lambda (e.g. Redis Enterprise).
2. Install hiredis library, which is a C-based client and allows the default redis client to perform better (https://github.com/redis/redis-py/blob/1a41cfd95a53a95b078084d8627be6b6fba3bb71/redis/utils.py#L4).

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

Allow using Redis online store in AWS Lambda feature server

[codecov-commenter]

Codecov Report

Merging #2057 (0033234) into master (3bbd4cf) will increase coverage by 25.14%.
The diff coverage is n/a.

❗ Current head 0033234 differs from pull request most recent head 9d8f1a8. Consider uploading reports for the commit 9d8f1a8 to get more accurate results

@@             Coverage Diff             @@
##           master    #2057       +/-   ##
===========================================
+ Coverage   58.31%   83.46%   +25.14%     
===========================================
  Files         100      100               
  Lines        8066     8066               
===========================================
+ Hits         4704     6732     +2028     
+ Misses       3362     1334     -2028     

Flag	Coverage Δ
integrationtests	73.87% <ø> (?)
unittests	58.31% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
sdk/python/feast/data_source.py	61.29% <0.00%> (+0.40%)	⬆️
sdk/python/feast/online_response.py	87.71% <0.00%> (+1.75%)	⬆️
sdk/python/feast/infra/online_stores/sqlite.py	96.77% <0.00%> (+2.15%)	⬆️
sdk/python/feast/feature.py	72.72% <0.00%> (+3.03%)	⬆️
sdk/python/feast/infra/provider.py	91.73% <0.00%> (+4.95%)	⬆️
sdk/python/feast/errors.py	70.00% <0.00%> (+5.00%)	⬆️
sdk/python/feast/infra/offline_stores/file.py	96.80% <0.00%> (+8.00%)	⬆️
sdk/python/feast/registry.py	80.76% <0.00%> (+10.48%)	⬆️
sdk/python/feast/feature_view.py	88.05% <0.00%> (+10.69%)	⬆️
sdk/python/feast/infra/passthrough_provider.py	100.00% <0.00%> (+11.11%)	⬆️
... and 49 more

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[adchia]

fyi @DvirDukhan

/lgtm

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