Set role when actpass remote to DTLSRoleClient

[Sean-Der]

This matches rfc5763, setup:active is RECOMMENDED

Relates to #494

[codecov]

Codecov Report

Merging #1258 into master will increase coverage by 0.33%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1258      +/-   ##
==========================================
+ Coverage   76.28%   76.62%   +0.33%     
==========================================
  Files          70       70              
  Lines        5334     5334              
==========================================
+ Hits         4069     4087      +18     
+ Misses        941      928      -13     
+ Partials      324      319       -5     

Flag	Coverage Δ
#go	79.00% <100.00%> (+0.38%)	⬆️
#wasm	69.70% <ø> (ø)

Impacted Files	Coverage Δ
dtlsrole.go	100.00% <ø> (ø)
dtlstransport.go	70.09% <100.00%> (+1.40%)	⬆️
peerconnection.go	77.64% <0.00%> (+0.19%)	⬆️
icetransport.go	74.82% <0.00%> (+1.39%)	⬆️
sctptransport.go	81.12% <0.00%> (+3.57%)	⬆️
internal/mux/mux.go	90.76% <0.00%> (+6.15%)	⬆️

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