Fix authority manager initialization during fast sync

[Harrm]

Referenced issues

Description of the Change

Authority manager tried to access the runtime storage without checking if it's possible.

Benefits

Kagome works properly when restarting fast sync.

Possible Drawbacks

None expected.

[codecov]

Codecov Report

Merging #1359 (d9c6b86) into master (0957e2a) will increase coverage by 0.00%.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master    #1359   +/-   ##
=======================================
  Coverage   24.17%   24.17%           
=======================================
  Files         627      627           
  Lines       23446    23449    +3     
  Branches    12258    12260    +2     
=======================================
+ Hits         5667     5669    +2     
- Misses      12503    12504    +1     
  Partials     5276     5276           

Impacted Files	Coverage Δ
...onsensus/authority/impl/authority_manager_impl.cpp	21.59% <0.00%> (-0.15%)	⬇️
core/api/transport/impl/ws/ws_listener_impl.cpp	43.05% <0.00%> (+2.77%)	⬆️

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