Rename `AccessPathSyntax` to `ImportPathSyntax`

[ahoppen]

Address this Fix-It.

https://github.com/apple/swift-syntax/blob/2179d9fe6335c54e2fb13419c1186ac549d407c2/CodeGeneration/Sources/SyntaxSupport/DeclNodes.swift#L33

Also rename any properties named accessPath. To keep existing clients building, provide a type alias that maps AccessPathSyntax to ImportPathSyntax and deprecated methods for accessPath to SwiftSyntaxCompatibility.swift

[ahoppen]

Tracked in Apple’s issue tracker as rdar://108812214

[whiteio]

@ahoppen Is it ok if I work on this one?

[ahoppen]

That would be great