Allow CodegenBackend to borrow from invoker of rustc_driver

[bjorn3]

I authored this change almost 6 years ago, but never had a good reason to submit it. I'm probably going to need it soon for some experiments on the cg_clif side, so I decided to upstream it now.

• I did not use an LLM to create a change in this PR.
• I used an LLM to create a change in this PR, and I have explained below how it was used.

[rustbot]

r? @mati865

rustbot has assigned @mati865.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

• Owners of files modified in this PR: compiler
• compiler expanded to 75 candidates
• Random selection from 19 candidates

[rust-log-analyzer]

The job pr-check-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

    |      ^^^^^^^^^^^^^^^^^^^^^^^ expected lifetime parameter
    |
help: indicate the anonymous lifetime
    |
115 | impl rustc_driver::Callbacks<'_> for DefaultCallbacks {}
    |                             ++++

error[E0726]: implicit elided lifetime not allowed here
   --> src/tools/clippy/src/driver.rs:123:6
    |
123 | impl rustc_driver::Callbacks for RustcCallbacks {
    |      ^^^^^^^^^^^^^^^^^^^^^^^ expected lifetime parameter
    |
help: indicate the anonymous lifetime
    |
123 | impl rustc_driver::Callbacks<'_> for RustcCallbacks {
    |                             ++++

error[E0726]: implicit elided lifetime not allowed here
   --> src/tools/clippy/src/driver.rs:137:6
    |
137 | impl rustc_driver::Callbacks for ClippyCallbacks {
    |      ^^^^^^^^^^^^^^^^^^^^^^^ expected lifetime parameter
    |
help: indicate the anonymous lifetime
    |
137 | impl rustc_driver::Callbacks<'_> for ClippyCallbacks {
    |                             ++++

[RUSTC-TIMING] lint_message_convention test:true 0.106
warning: hidden lifetime parameters in types are deprecated
   --> src/tools/clippy/src/driver.rs:124:50