refactor: Rename LayoutBuilderRow.EqualCols to Columns

After repeated use the Equal term is awkward.

feat: Add LayoutBuilderRow.RowOffset to offset an entire row

Prior to this change, applying an offset to an entire row can be cumbersome and also need to be applied to every subsequent row (if desired). This helper makes it easier to adjust a row (and all following rows).

Minor cleanup for new Painter Layout functionality

* Fixes Row layout builder modifying the builder state on Build()
* Improves error checking for when pixel bounds specify beyond the painters boundary

fix: ChartOption preserve series colors when combining chart types

In v0.5.0 we updated the series structs to be chart type specific. This resulted in the filter operation completely removing different types from the series slice.

The above change resulted in the bug of after series filtering each chart type would be referencing the series starting from index 0.

This change fixes that behavior by adding an `absThemeIndex` to series types which can be combined. This internal field is set when sourced from a `GenericSeries` to ensure the original series ordering is communicated to the chart rendering.

Tests were added to cover this behavior, which also highlighted that our chart rendering order could be improved for readability as well.

build(deps): bump github.com/stretchr/testify from 1.11.0 to 1.11.1

Bumps [github.com/stretchr/testify](https://github.com/stretchr/testify) from 1.11.0 to 1.11.1.
- [Release notes](https://github.com/stretchr/testify/releases)
- [Commits](stretchr/testify@v1.11.0...v1.11.1)

---
updated-dependencies:
- dependency-name: github.com/stretchr/testify
  dependency-version: 1.11.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

feat: Allow individual series label customization

Prior to this change all data labels had to be enabled or disabled, as well as with a matching style. This left mark points to be the only way to highlight specific values.

With this change a `SeriesLabelFormatter` can now be set on the `SeriesLabel` struct. This function allows for selective hidding of values (by returning an empty string), as well as selective changes to the text style or a background behind the label.

This is designed for emphasizing specific values, and with that `LabelFormatterThresholdMin`, `LabelFormatterTopN`, `LabelFormatterProgressiveGreenRed`, and `LabelFormatterProgressiveColor` were added as helpers to easily highlight upper values.

`SeriesLabel.FormatTemplate` has been deprecated to be removed in `v0.6.0`.  The new `LabelFormatter` function is a more powerful alternative.

docs: Improve Issue Templates

ci: Add `go vet` to `lint`

fix: Fix for preferring smaller label counts when unit is used

This change fixes a regression introduced in the prior change (v0.5.12). The improved unit label count / span logic failed to have a preference for more labels. Resulting in cases where two labels are equally good as charts where every value is labeled.
This updates the conditional to prefer higher label counts when the delta from the padded label count is the same.

fix: Range better handling for determining the max when a unit is spe…

…cified

The change in 7d38925 fixed an infinite loop, but resulted in potentially a very large max range calculation, which would take forever to render.

This redos that logic using a mechanism which loops less, while still doing a comparision to pick the best possible result.