[clang-repl] Delegate CodeGen related operations for PTU to IncrementalParser (#137458)

Read discussion : https://github.com/llvm/llvm-project/pull/136404#discussion_r2059149768
and the following comments for context

Motivation
1) `IncrementalAction` is designed to keep Frontend statealive across
inputs. As per the docstring: “IncrementalAction ensures it keeps its
underlying action's objects alive as long as the IncrementalParser needs
them.”
2) To align responsibilities with that contract, the parser layer (host:
`IncrementalParser`, device: `IncrementalCUDADeviceParser`) should
manage PTU registration and module generation, while the interpreter
orchestrates at a higher level.

What this PR does
1) Moves CodeGen surfaces behind IncrementalAction:
GenModule(), getCodeGen(), and the cached “first CodeGen module” now
live in IncrementalAction.

2) Moves PTU ownership to the parser layer:
Adds IncrementalParser::RegisterPTU(…) (and device counterpart)

3) Add device-side registration in IncrementalCUDADeviceParser.

4) Remove Interpreter::{getCodeGen, GenModule, RegisterPTU}.

0 files changed, 0 insertions, 0 deletions