Make max number of autoimport suggestions configurable

[kldtz]

Problem: Currently the maximum number of results for autoimport completions and code actions is hard-coded:

python-lsp-server/pylsp/plugins/rope_autoimport.py

Lines 26 to 27 in c8e4e99

	MAX_RESULTS_COMPLETIONS = 1000
	MAX_RESULTS_CODE_ACTIONS = 5

For the completions it's not an issue because the number is large enough, but for code actions it often cuts off useful suggestions. I first thought that something was broken until I found these constants in the code.

Solution: I'd like to add two optional settings for these values. The default would be the current values, so it'd be a non-breaking change. I could open a PR for this.