Klive handshake docs py2

[joamatab]

• adds klive handshake for more reliable
• prints warning when running component.show() and klayout is not open
• allows to delete file after showing it
• organize notebooks in flat structure

[codecov]

Codecov Report

Merging #1796 (1f87b9f) into main (401369a) will decrease coverage by 0.03%.
The diff coverage is 25.00%.

@@            Coverage Diff             @@
##             main    #1796      +/-   ##
==========================================
- Coverage   68.43%   68.41%   -0.03%     
==========================================
  Files         374      374              
  Lines       23574    23584      +10     
  Branches     3413     3414       +1     
==========================================
+ Hits        16133    16135       +2     
- Misses       6488     6495       +7     
- Partials      953      954       +1     

Impacted Files	Coverage Δ
gdsfactory/add_loopback.py	26.66% <ø> (ø)
gdsfactory/klive.py	54.83% <25.00%> (-16.59%)	⬇️

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