Fix shutdown issues

[chenyukang]

Fixes #503
Fixes #333

Changes including:

1. Refactor shutdown-related code, merge the logic of tracing transaction (tx) within the force shutdown to the normal shutdown logic
2. Channel status is changed to "Closed" status only after the trace tx returns a confirmed result.
3. Fix the issue of the error in the first hop wasn't recorded in the payment session fb04bb9#diff-176f6d4f89e68f8dda8ca44f71496fbfc28d7fbf135f1b5f2795c8a183a0bc18L1736-R1749
4. Remove tlc waiting for ack when shutdown procedure started 12bd2fb

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 90.52632% with 18 lines in your changes missing coverage. Please review.

Project coverage is 50.27%. Comparing base (d8b1917) to head (19f3ed5).

Files with missing lines	Patch %	Lines
src/fiber/channel.rs	90.66%	14 Missing ⚠️
src/fiber/network.rs	90.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #516      +/-   ##
===========================================
+ Coverage    50.02%   50.27%   +0.25%     
===========================================
  Files           49       49              
  Lines        32389    32442      +53     
===========================================
+ Hits         16201    16309     +108     
+ Misses       16188    16133      -55     

Flag	Coverage Δ
unittests	50.27% <90.52%> (+0.25%)	⬆️

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