fix: ban peers when do reorg after client restart

[yangby-cryptape]

Description

This PR will fix #145.

If the first new "last state" after light client restarted is a fork state, the light client will do reorg to change its state to the new chain.

Let's denote

• the number of old "last state" as $n_{old}$.
• the number of new "last state" as $n_{new}$.
• the parameter LAST_N_BLOCKS as $N$.

The blocks before $n_{old}$ (included) are called as "reorg blocks", "reorg blocks" must be continuous.
The last n continuous blocks before $n_{new}$ (included) are called as "last n blocks"; non-continuous blocks are "sampled blocks".

If the restart is too soon, $n_{new} - n_{old} < N$, the "last n blocks" will not enough, then light client will throw the error InvalidReorgHeaders and ban the peer who sent the proof.

How to fix?

If light client received all blocks between the fork block to the new "last state", then light client could use the reorg blocks to fill the "last n blocks".

Commits

• test: reproduce the bug that peers will be banned when do reorg after client restart
• fix: ban peers when do reorg after client restart

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (e0a060a) 71.14% compared to head (78e099a) 71.41%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #166      +/-   ##
===========================================
+ Coverage    71.14%   71.41%   +0.26%     
===========================================
  Files           25       25              
  Lines         6457     6478      +21     
===========================================
+ Hits          4594     4626      +32     
+ Misses        1863     1852      -11     

Flag	Coverage Δ
unittests	71.41% <100.00%> (+0.26%)	⬆️

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