new bar_mode option to allow bidirectionality

[Ndrinta]

Hi, this adds the option to go "bidirectionally" CV and CCW from the top ('0').
To use, simply add the option bar_mode: bidirectional (or "normal" for default behavior).
Backwards compatible because if unused it defaults using the "normal" mode, hence nothing changes for uninterested users.

      // Bidirectional: zero at top, positive CW, negative CCW
      // Assume min < 0 < max

I've been testing this for about 6 months now and seems stable.

[Ndrinta]

Usage example:

type: custom:flex-horseshoe-card
view_layout:
  grid-area: block1
entities:
  - entity: sensor.grid_ct_w
    decimals: 0
    unit: W
    name: GRID
  - entity: sensor.grid_daily
    decimals: 1
    unit: kWh
    icon: mdi:transmission-tower-export
  - entity: sensor.feed_in_energy_today
    decimals: 1
    unit: kWh
    icon: mdi:transmission-tower-import
show:
  horseshoe_style: colorstopgradient
layout:
  hlines:
    - id: 0
      xpos: 50
      ypos: 42
      length: 40
      styles:
        - stroke: grey;
        - stroke-width: 5;
        - stroke-linecap: round;
        - opacity: 0.7;
  states:
    - id: 0
      entity_index: 0
      xpos: 50
      ypos: 34
      styles:
        - font-size: 3em;
    - id: 1
      entity_index: 1
      xpos: 40
      ypos: 57
      styles:
        - text-anchor: start;
        - font-size: 1.7em;
    - id: 2
      entity_index: 2
      xpos: 40
      ypos: 72
      styles:
        - text-anchor: start;
        - font-size: 1.7em;
  icons:
    - id: 0
      entity_index: 1
      xpos: 37
      ypos: 57
      align: end
      size: 1.3
    - id: 1
      entity_index: 2
      xpos: 37
      ypos: 72
      align: end
      size: 1.3
  names:
    - id: 0
      entity_index: 0
      xpos: 50
      ypos: 95
horseshoe_scale:
  min: -6500
  max: 6500
  color: lightgrey
bar_mode: bidirectional
color_stops:
  "0": var(--energy-grid-consumption-color)
  "100": var(--energy-grid-return-color)

[meizenga]

this is what we're looking for to support grid/battery consumption/production using a single entity which also has negative values