Improve code auto-completion

[CodingOctocat]

The current code completion uses the Tab key to submit, and it is proposed to support more keystroke submissions(Space, (, [, .):

This avoids frequent use of the Tab key.

current behavior：
pri -> Tab -> ( => print()
improve：
pri -> ( => print()

current behavior：
my_o -> Tab -> . -> prop -> Tab => my_obj.property1
improve：
my_o -> . -> prop -> Space/Tab => my_obj.property1

[Calinou]

Pressing Space to accept autocompletion suggestions is pretty uncommon in most editors. You should already be able to add this binding in the Editor Settings' shortcuts tab, but I don't think it should be the default.

[CodingOctocat]

@Calinou Maybe I didn't describe it very well, most IDEs (Visual Studio, PyCharm, Rider) support (Space, (, [, . ), where the IDE submits the candidate and then types the symbols, which is equivalent to merging the submit and symbol operations.

Space are common because programming languages use spaces as separators, as shown below.

1. pub -> Tab -> Space -> Foo It can be simplified to： pub -> Space -> Foo
2. myd -> Tab -> . -> A -> Tab -> ( -> 1 It can be simplified to：myd -> . -> ( -> 1