feat: use websocket stream block listener

[atanmarko]

Description

Change block retrieval from the subnet node. Use websocket stream block subscription instead of timer.

Fixes TP-599

Additions and Changes

Old mechanism to retrieve block by number is kept for initial block sync on sequencer startup. When sync is performed, blocks are further received though block subscription stream.

PR Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added or updated tests that comprehensively prove my change is effective or that my feature works

[codecov]

Codecov Report

Attention: 74 lines in your changes are missing coverage. Please review.

Comparison is base (4799cce) 60.92% compared to head (c035507) 60.61%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #371      +/-   ##
==========================================
- Coverage   60.92%   60.61%   -0.32%     
==========================================
  Files         233      233              
  Lines       12282    12352      +70     
==========================================
+ Hits         7483     7487       +4     
- Misses       4799     4865      +66     

Files	Coverage Δ
crates/topos-sequencer-subnet-runtime/src/proxy.rs	0.00% <0.00%> (ø)
crates/topos-sequencer-subnet-client/src/lib.rs	0.00% <0.00%> (ø)

... and 1 file with indirect coverage changes

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