Extend CI with building for iOS

[valeriyvan]

Running swift build --triple aarch64-apple-ios-sim produces errors unable to load standard library for target 'aarch64-apple-ios12.0-sim:

swift build --triple aarch64-apple-ios-sim --sdk "`xcrun --sdk iphonesimulator --show-sdk-path`"
warning: 'swift-algorithms': found 1 file(s) which are unhandled; explicitly declare them as resources or exclude from the target
    /Users/***/swift-geometrize/.build/checkouts/swift-algorithms/Sources/Algorithms/Documentation.docc
Building for debugging...
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
error: emit-module command failed with exit code 1 (use -v to see invocation)
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
error: emit-module command failed with exit code 1 (use -v to see invocation)
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios16.4-sim'
error: emit-module command failed with exit code 1 (use -v to see invocation)
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios16.4-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
error: emit-module command failed with exit code 1 (use -v to see invocation)
<unknown>:0: error: unable to load standard library for target 'aarch64-apple-ios12.0-sim'
[25/29] Emitting module SwiftJPEG