[Feature Request] Add "input" type to VSkeletonLoader

Problem to solve

Use case: form inputs that require an asynchronous call to be populated.

The button type is the closest type to matching this, but it doesn't really fit the styling of an input. This would benefit developers who have asynchronous forms which they would like to use a skeleton loader on, providing users with feedback on the state of the form in a style that is visually consistent with the form itself.

Proposed solution

A simple "input" type would suffice initially, directly covering selects, text fields, and autocompletes, some of the most common form types. Additional types would be potentially valuable for representing textareas, selection controls, and other minor form fields, though I think these could be adequately represented with the "input" type initially.

Visually, I think the best styling would approximately match the "filled" style of inputs, consistent with the current styling of skeleton loader types.

I'm willing to submit a pull request with a proposed implementation if that would be beneficial.