Heuristic/loose completions for the 'any' type

Motivation

Today, if you have a value of type 'any', dotting off of the value and requesting members for completion will return nothing back. The original motivation for this was that we should never risk giving users incorrect completions.

This is great for a fully typed TypeScript project. However, for those migrating to TypeScript, as well as those who need to drop down to any fairly frequently, this can be slightly frustrating.

For those used to the JS editing experience in editors like Sublime where they just "got completions", the current behavior might be seen as unattractive.

Proposal

We should consider adding a language service option for users to get "loose" completions akin to what we give in the Salsa language service.

We can still keep the warning for each completion, but we should provide completions with a builder.

まず提案を読み、issueで言及されている既存のSalsa language-serviceの動作と比較します。loose completions向けのlanguage-serviceオプションの範囲を明確にします。これには、警告をどのように関連付けたままにするべきか、またこの機能が完成したと判断できるcompletionの動作が含まれます。