Timeout support

[carson-katri]

Adds a Timeout RequestParam, as well as a new unit test to cover the timeout.

Timeout(60)
Timeout(60, for: .request)
Timeout(60, for: .resource)

[codecov-commenter]

Codecov Report

Merging #27 into master will increase coverage by 0.14%.
The diff coverage is 91.17%.

@@            Coverage Diff             @@
##           master      #27      +/-   ##
==========================================
+ Coverage   86.03%   86.17%   +0.14%     
==========================================
  Files          21       22       +1     
  Lines         716      745      +29     
==========================================
+ Hits          616      642      +26     
- Misses        100      103       +3     

Impacted Files	Coverage Δ
Sources/Request/Request/RequestParams/Body.swift	100.00% <ø> (ø)
Sources/Request/Request/RequestParams/Method.swift	100.00% <ø> (ø)
...ces/Request/Request/RequestParams/QueryParam.swift	100.00% <ø> (ø)
...s/Request/Request/RequestParams/RequestParam.swift	60.00% <33.33%> (-40.00%)	⬇️
Sources/Request/Request/Request.swift	93.04% <91.66%> (-0.23%)	⬇️
Sources/Request/Request/RequestParams/Header.swift	100.00% <100.00%> (ø)
...ources/Request/Request/RequestParams/Timeout.swift	100.00% <100.00%> (ø)
Tests/RequestTests/RequestTests.swift	93.56% <100.00%> (+0.27%)	⬆️

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