Fix rustc warnings about unused 'pub use's

[the-mikedavis]

Newer rustc versions warn about these unused exports. On rustc 1.76.0 for example:

warning: unused import: `helix_view::handlers::lsp::SignatureHelpInvoked`
  --> helix-term/src/handlers.rs:12:9
   |
12 | pub use helix_view::handlers::lsp::SignatureHelpInvoked;
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(unused_imports)]` on by default

warning: unused import: `keymap::macros::*`
  --> helix-term/src/lib.rs:23:9
   |
23 | pub use keymap::macros::*;
   |         ^^^^^^^^^^^^^^^^^

warning: `helix-term` (lib) generated 2 warnings (run `cargo fix --lib -p helix-term` to apply 2 suggestions)