Tidy up PE dashboard

[david-martin]

• consistent colouring with Refine the app developer dashboard #540
• add panels for healthy/unhealty gateways
• aggregate into 2 rows (gateways & apis) instead of 3 rows
• add text box at top with summary of dashboard and httproute labelling info
• remove the deployments table as it felt out of place
• use shared crosshair for time series
• use hue gradient in time series
• use 'all' tooltip mode on time series

I couldn't get it to use different shades of yellow only for the errors time series. I went with a yellow to red option, which may be the best option there to try keep close to a yellow colour for errors.

[codecov]

Codecov Report

Merging #542 (477f246) into main (ece13e8) will increase coverage by 0.73%.
Report is 34 commits behind head on main.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #542      +/-   ##
==========================================
+ Coverage   80.20%   80.94%   +0.73%     
==========================================
  Files          64       71       +7     
  Lines        4492     4990     +498     
==========================================
+ Hits         3603     4039     +436     
- Misses        600      641      +41     
- Partials      289      310      +21     

Flag	Coverage Δ
integration	71.92% <ø> (+0.64%)	⬆️
unit	33.52% <ø> (+3.48%)	⬆️

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

Components	Coverage Δ
api/v1beta1 (u)	71.42% <ø> (ø)
api/v1beta2 (u)	88.81% <100.00%> (-2.62%)	⬇️
pkg/common (u)	83.01% <ø> (-5.81%)	⬇️
pkg/istio (u)	75.14% <100.00%> (+1.23%)	⬆️
pkg/log (u)	94.73% <ø> (ø)
pkg/reconcilers (u)	∅ <ø> (∅)
pkg/rlptools (u)	79.84% <ø> (+0.39%)	⬆️
controllers (i)	77.39% <81.96%> (+0.59%)	⬆️

see 16 files with indirect coverage changes

[R-Lawton]

Looks great