Fix decoding 'flag' URL query params via .decode(StructType.self)

[challfry]

These changes are now available in 4.101.3

Fixes #3163.

The code:

struct QueryStruct: Content {
    var flag1: Bool?
}
let queryStruct = try req.query.decode(QueryStruct.self)

produces queryStruct.flag1 == true when decoding the URL query "?flag1", matching the behavior of req.query[Bool.self, at: "flag1"].

[0xTim]

Thanks!

@gwynne any thoughts?

[0xTim]

@challfry could you fix the conflicts?

[gwynne]

I'm okay with it, once the conflicts are fixed

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.63%. Comparing base (11cdb29) to head (d124dcd).
Report is 28 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3164      +/-   ##
==========================================
+ Coverage   76.86%   77.63%   +0.76%     
==========================================
  Files         211      210       -1     
  Lines        8119     8137      +18     
==========================================
+ Hits         6241     6317      +76     
+ Misses       1878     1820      -58     

Files	Coverage Δ
...s/Vapor/URLEncodedForm/URLEncodedFormDecoder.swift	85.25% <100.00%> (-0.56%)	⬇️

... and 95 files with indirect coverage changes

[challfry]

Merge conflicts fixed.

For the failing vapor/jwt test, it appears jwt-kit changed part of their API last week, and jwt's JWTTests.swift is yet to be updated.