Add demo book app watcher for terminal and raw JSON from web API

[trstringer]

Description:

When I'm testing or demo'ing OSM, I am in the terminal. The demo app requires you to use the browser or curl the markup of the different services (bookbuyer, bookthief, etc.). This is very manual and requires some visual grep'ing as well as manual refreshing.

This PR adds a /raw route to bookbuyer, bookthief, and bookstore to get their JSON data. It also adds a bookwatcher bin that polls the different raw endpoints and displays the output. The text color is as follows:

• Yellow - data hasn't changed since last poll iteration
• Green - data for bookbuyer and bookstore has changed
• Red - books were stolen by the bookthief since last poll iteration

This refreshes the terminal every second. Below are screenshots showing the experience.

Affected area:

Functional Area
Demo	[X]

Testing done:

This shows that since the last iteration, the bookbuyer has bought a book (or books) and the bookstore V1 has sold a book (or books).

This shows that since the last iteration, the bookthief has stolen a book (or books) and bookstore V1 has sold a book (or books).

Please answer the following questions with yes/no.

1. Does this change contain code from or inspired by another project?

No.

2. Is this a breaking change?

No.

[codecov-commenter]

Codecov Report

Merging #3930 (c07dad1) into main (8ed34b1) will decrease coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3930      +/-   ##
==========================================
- Coverage   67.61%   67.49%   -0.12%     
==========================================
  Files         202      202              
  Lines       11504    11543      +39     
==========================================
+ Hits         7778     7791      +13     
- Misses       3676     3702      +26     
  Partials       50       50              

Flag	Coverage Δ
unittests	67.49% <ø> (-0.12%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
cmd/init-osm-controller/init-osm-controller.go
cmd/osm-bootstrap/osm-bootstrap.go	33.64% <0.00%> (ø)
cmd/osm-controller/osm-controller.go	14.01% <0.00%> (+0.43%)	⬆️
pkg/envoy/rds/route/route_config.go	100.00% <0.00%> (+3.64%)	⬆️

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