rustic configures eglot when rustic-lsp-setup-p is nil

[lunik1]

Issue rustic will always alter eglot-server-programs, even when rustic-lsp-setup-p is nil.

Motivation This makes it difficult to alter the initialisation options sent to rust-analyzer, as these are not exposed. A customised definition of rust-analyzer to set such options in eglot-server-programs will usually be clobbered.

Expected behaviour rustic-lsp-setup-p set to nil should not configure eglot

Notes It would also be nice if the user could set initialisation options of the lsp server through rustic.

[parbo]

I need this fixed to be able to turn on clippy checks in rust-analyzer diagnostics.