Use systems = @named begin .. end idiom to define systems in tutorials

[jaakkor2]

Tutorials list all systems in the ODESystem()-function call. This is cumbersome, and one easily forgets to append
the list after adding the actual system and its connections.

systems = @named begin
 ..
end

is a more user friendly pattern.

[jaakkor2]

Huh,

Run julia -e '
┌ Error: Some files have not been formatted !!!
└ @ Main none:6
docs/pages.jl
src/Hydraulic/IsothermalCompressible/components.jl
Error: Process completed with exit code 1.

I did not touch src/Hydraulic/IsothermalCompressible/components.jl nor docs/pages.jl.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 54.35%. Comparing base (76b07b3) to head (c66d73a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #295      +/-   ##
==========================================
- Coverage   61.56%   54.35%   -7.22%     
==========================================
  Files          46       46              
  Lines        1470     1665     +195     
==========================================
  Hits          905      905              
- Misses        565      760     +195     

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