Distinguish between SessionWithConnections and SessionWithConnectionEditing

[cmdcolin]

This formalizes some code that checks for 'session.makeConnection' (which embedded has) to be a SessionWithConnections and then 'session.addConnectionConf' to be SessionWithConnectionEditing (which embedded may not have)

Also cleans up the typescript a little (less use of Function)

[codecov]

Codecov Report

Merging #3741 (2204276) into main (463c4dc) will decrease coverage by 0.04%.
The diff coverage is 22.72%.

@@            Coverage Diff             @@
##             main    #3741      +/-   ##
==========================================
- Coverage   64.35%   64.32%   -0.04%     
==========================================
  Files         977      977              
  Lines       29897    29902       +5     
  Branches     7172     7179       +7     
==========================================
- Hits        19240    19233       -7     
- Misses      10491    10500       +9     
- Partials      166      169       +3     

Impacted Files	Coverage Δ
...idget/components/dialogs/CloseConnectionDialog.tsx	0.00% <0.00%> (ø)
...ckSelectorWidget/components/tree/HamburgerMenu.tsx	31.34% <16.66%> (-7.72%)	⬇️
packages/core/util/types/index.ts	71.57% <100.00%> (+0.61%)	⬆️

... and 3 files with indirect coverage changes

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