[Enhancement] Enhance the completion experience of KCL Import for both internal and external packages

[Peefy]

Enhancement

For the following module

.
├── kcl.mod
├── kcl.mod.lock
├── main.k
└── tt
    └── tt.k

The content of kcl.mod is

[package]
name = "m"
edition = "v0.9.0"
version = "0.0.1"

[dependencies]
k8s = { oci = "oci://ghcr.io/kcl-lang/k8s", tag = "1.29" }

The import stmt in main.k should be enhanced

The completion items should contains tt and k8s