Discussion: support a uniformed alias comprehension manner

[kirk0830]

Background

There are users sometimes mess up the value expected to assign keyword, such as what issue #5948 mentions, the gau for smearing_method case.
However, whether the alias should be supported is a question needed to discuss. Points are:

1. This will affect how the parameter/input module works, for the most convienent way to handle those alias is first let all keywords supporting alias pre-process by their specific function, like what I implement in this PR.
2. Although this provides somehow the easy-to-use feature for user and partially improves the user-friendliness, this will bring more difficulties when debugging the input script when ABACUS crashes and no useful information pop, like "something went wrong when reading atom position", this is, not clear at all.

@Qianruipku @QuantumMisaka

Linked Issue

Fix #5948

[kirk0830]

For I get no response, I will close this PR temporarily

[QuantumMisaka]

In my perspective, the less alias the better.