Refactor header exchange to accommodate block exchange service

[Manav-Aggarwal]

Overview

Closes: #1029

Checklist

• New and updated code has appropriate documentation
• New and updated code has new and/or updated testing
• Required CI checks are passing
• Visual proof for any user facing features like CLI or documentation updates
• Linked issues closed with keywords

[codecov]

Codecov Report

Patch coverage: 30.61% and project coverage change: -0.54 ⚠️

Comparison is base (9564421) 54.91% compared to head (fcd09d9) 54.38%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1028      +/-   ##
==========================================
- Coverage   54.91%   54.38%   -0.54%     
==========================================
  Files          63       63              
  Lines        6628     6643      +15     
==========================================
- Hits         3640     3613      -27     
- Misses       2611     2642      +31     
- Partials      377      388      +11     

Impacted Files	Coverage Δ
node/full.go	65.40% <16.66%> (-3.57%)	⬇️
node/header_exchange.go	46.42% <32.55%> (-6.65%)	⬇️

... and 3 files with indirect coverage changes

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[gupadhyaya]

When the aggregator publishes the genesis block, it initializes its header store using the genesis header and tries to start the syncer: https://github.com/rollkit/rollkit/blob/main/node/header_exchange.go#L99
The syncer as part of Start process, tries to check if the genesis header found in the header store is recent (https://github.com/celestiaorg/go-header/blob/main/sync/sync_head.go#L24). This check requires that the genesis header time is not older than 1.5x blocktime.
If the blocktime is too short, the time between the genesis header creation and the isRecent check exceeds the 1.5x blocktime which leads to the genesis header obtained from the header store as not recent. Hence the error, header: not found.

[gupadhyaya]

@Manav-Aggarwal i think your merge commit has overwritten my changes.

[Manav-Aggarwal]

@Manav-Aggarwal i think your merge commit has overwritten my changes.

Just rebased again, looks the same. If it's the go.mod file changes, the go-header version upgrade is updated in main already.