Implements feature request: #4313

[rosco54]

Provide a "step before" version of the current "step after" line chart.

API:
Retain the existing "stepline" curve type for backward compatibility and denote the new type as "linestep".

Perhaps read these as "step follows line" and "line follows step" respectively.

Example:

stroke: {
curve: 'linestep'
}

Add e2e sample: source/line/linestep.xml and derived (built) samples.

Fixes #4313

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[junedchhipa]

Please add types for this option in types/apexcharts.d.ts