Update docs to include Snowflake/DQM and removing unused docs from old versions of Feast

[adchia]

What this PR does / why we need it:
Update docs (and hero image) to include Snowflake/DQM and removing unused docs from old versions of Feast. This also includes updating of the roadmap + quickstart to reflect the current state of Feast

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

NONE

[codecov-commenter]

Codecov Report

Merging #2268 (587f9d8) into master (6e30457) will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2268      +/-   ##
==========================================
+ Coverage   85.82%   85.85%   +0.03%     
==========================================
  Files         116      116              
  Lines        9790     9790              
==========================================
+ Hits         8402     8405       +3     
+ Misses       1388     1385       -3     

Flag	Coverage Δ
integrationtests	74.61% <ø> (-0.29%)	⬇️
unittests	58.52% <ø> (ø)

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

Impacted Files	Coverage Δ
.../integration/online_store/test_universal_online.py	97.50% <0.00%> (-0.42%)	⬇️
sdk/python/feast/infra/online_stores/datastore.py	90.56% <0.00%> (+1.88%)	⬆️

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[felixwang9817]

/lgtm

[feast-ci-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: adchia, felixwang9817

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