Visualize Item Floats in a Floatbar (Market + Inventory)

[GODrums]

Motivation

Floats can be a pretty confusing concept at first glance. To illustrate the basics of low/high-floats, we want to introduce a float-bar, which visualizes an item's float according to all possible values in a colored bar.
Solves #9.

Description

This PR contains a new float-bar component:

• New UI-Component: FloatBar (LitElement) inspired by the floatbar on the CSFloat website:
  • Can be re-used as HTML-element in any component: <float-bar></float-bar>
  • Bar is limited according to provided min/max-float values
  • White marker at the actual item float
  • Opacity of 0.8 to adjust color-spectrum to Steam's "dark theme"
• Adds FloatBar to inventory-page
• Adds FloatBar to market-page and limits its width in a responsive manner

Possible follow-ups:

• Tooltip with more "details" such as the min/max floats in text format
• Actual Float as "hover" above the float-marker

Screenshots

Floatbar in the inventory:

Floatbar on the market:

Floatbar on the market (mobile):

[Step7750]

Thanks @GODrums, looks great!

Left a few code-style comments, nits are optional. The tooltip with details such as min/max float would be cool, but it'd probably a decent amount of work to make a re-usable tooltip system -- your choice whether you want to implement that in a follow up!