feat(core,track): move gosling-theme to this repo, support more compact genomic axis style

[sehilyi]

Fix #990
Fix #860

Change List

• Moved the gosling-theme repository to this repo (Had to fix some typescript errors that were there) Include gosling-lang/gosling-theme to this repo #860
• Added two options of axis theme (labelMargin and labelExcludeChrPrefix) Genomic axis hides chr<N> labels #990

(Changes after moving the gosling-theme repo can be found at 7d5fd40...d924a9d)

labelMargin

The margin around labels for calculating visual overlaps between labels. This is mainly used for determining the visibility of axis labels. 0 if no margin to use. Negative values (-1) for showing all labels even if they overlap.

labelExcludeChrPrefix

If true, labels of genomics axes excludes the chromosome prefix (e.g., chr1 -> 1).

Screenshots

Default (labelMargin == 5, labelExcludeChrPrefix == false)

labelMargin == 0, labelExcludeChrPrefix == false

labelMargin == -1, labelExcludeChrPrefix == false

labelMargin == -1, labelExcludeChrPrefix == true

Checklist

• Ensure the PR works with all demos on the online editor
• Unit tests added or updated
• Examples added or updated
• Documentation updated (e.g., added API functions)
• Screenshots for visual changes (e.g., new encoding support or UI change on Editor)

[thomcsmits]

Very nice! Two things:

• I don't think the labelMargin is very intuitive, so we need to add good documentation for this
• When two labels are too overlapping, then the second is hidden (I suppose?), but I can imagine users want to specify specifically the labels they want to show (for e.g. figure for paper), perhaps we should also add this option

[etowahadams]

Looks good to me. Glad to have the gosling themes moved to this repo.
Once this gets merged into master, I'll copy over the schema into the gosling-website and update the docs