* add `NominalTypeDecl.isResilient`
* make the return type of `Type.getNominalFields` optional and return nil in case the nominal type is resilient.
This forces users of this API to think about what to do in case the nominal type is resilient.
add field types:
`x`: existential address projection, like `open_existential_addr`
`i<n>`: indexed element with constant index, like `index_addr` with an integer literal as index
`i*`: indexed element with an unknown index
Let's lldb's `po` command not print any "internal" properties of the conforming type.
This is useful if the `description` already contains all the information of a type instance.
* "merge" the `Path` and `State` in WalkUtils into a single `WalkingPath`. This makes it simpler for clients to configure a path and additional state variables. EscapeInfo now defines `EscapePath` which includes the projection path and EscapeInfo's specific state variables.
* Make the `WalkerCache` part of the WalkUtils, so that not all clients have to re-implement it.
* Rename `walkDownResults` -> `walkDownAllResults` and `walkUpOperands` -> `walkUpAllOperands` and make these functions client configurable.
`EscapeInfo` now conforms to the generic protocols defined in `WalkUtils`.
This simplifies the implementation a bit, since trivial instructions are handled
by `WalkUtils` and `EscapeInfo` only has to handle a subset of instructions
inherent to escape information.
Passes using `EscapeInfo` are updated accordingly to become visitors that
customize the `EscapeInfo` walk.
The `SmallProjectionPath` represents a path of value or address projections.
It’s used for defining argument effects for functions and for the new escape analysis.
