Add a sir-compiler-bridge module that adds Kotlin and C bridges
for SIR. As SIR is still WIP, the module accepts `BridgeRequest`
instances instead of SIR elements.
New modules 'sir', 'sir-passes', and 'sir-analysis-api' were added under
'native:swift' for creating and manipulating Swift IR elements.
* `sir` contains the implementation of Swift IR.
* `sir-analysis-api` contains translation from Analysis API to SIR.
* `sir-passses` contains transformation passes.
This groundwork will allow to progress with the Swift IR.
Sergey Bogolepov