fix: Unhandled terminal mode in set_cursor implementation

[friedow]

Summary of the change
The set_cursor function on the blink.cmp.Context did not handle terminal mode gracefully. Since terminal buffers support using the vim.api.nvim_win_set_cursor function we can just extend the default behavior of set_cursor for terminal buffers.

How I noticed the problem:
Every time I've tried to switch to the third (or more) completion entry by hitting my select_next keybind in a terminal buffer I ran into this error:

Error executing vim.schedule lua callback: ...t/blink.cmp/lua/blink/cmp/completion/trigger/context.lua:106: Unsupported mode for setting cursor: term
stack traceback:
	[C]: in function 'assert'
	...t/blink.cmp/lua/blink/cmp/completion/trigger/context.lua:106: in function 'set_cursor'
	...ckages/start/blink.cmp/lua/blink/cmp/completion/list.lua:241: in function 'undo_preview'
	...ckages/start/blink.cmp/lua/blink/cmp/completion/list.lua:167: in function 'cb'
	...ckages/start/blink.cmp/lua/blink/cmp/lib/term_events.lua:81: in function 'suppress_events_for_callback'
	...tart/blink.cmp/lua/blink/cmp/completion/trigger/init.lua:201: in function 'suppress_events_for_callback'
	...ckages/start/blink.cmp/lua/blink/cmp/completion/list.lua:166: in function 'select'
	...ckages/start/blink.cmp/lua/blink/cmp/completion/list.lua:196: in function 'select_next'
	.../myNeovimPackages/start/blink.cmp/lua/blink/cmp/init.lua:189: in function <.../myNeovimPackages/start/blink.cmp/lua/blink/cmp/init.lua:189>

Why I noticed the problem
I'm currently building zsh completions for blink.cmp. More on that in other PRs in a couple of days :).

[Saghen]

Thanks!

I'm currently building zsh completions for blink.cmp. More on that in other PRs in a couple of days :)

If you've got any questions, please don't hesitate to comment on that issue!