Enhancing block tree viewer

[terencechain]

Made the following enhancements to block tree viewer (http://localhost:8080/tree)

Change list:

• Removed index field. Proposers don't care which index the block is in the proto array. This info was too low level
• Removed best descendent field. Proposers don't care the index of the best descendent and the best descendent can be seen as green
• Added graffiti field. It makes it easier to debug whose proposers submitted the forked blocks. Super useful to debug multi client testnet. If we agree this is too verbose, we also can remove it before mainnet.

[codecov]

Codecov Report

Merging #5880 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5880   +/-   ##
=======================================
  Coverage   60.22%   60.22%           
=======================================
  Files         314      314           
  Lines       27356    27356           
=======================================
  Hits        16475    16475           
  Misses       8659     8659           
  Partials     2222     2222