feat(performance): changed featureIcon to data URL at creation

[DamonU2]

Closes #2719

Description

featureIcon changed to string from HTML canvas element. Now changed to a data URL before assignment. Feature highlight for points now uses a set value for the size of the highlight circle.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

https://damonu2.github.io/geoview/outlier-ESRI-maxRecordCount.html Feb. 6 at 2:20 Eastern

Best way to see the speed increase in the data table is to load both tables and then switch between them - no query, you just see how long to render. Tried the same for loading the map - keeping layer info in cache and reloading.

Checklist:

• I have build (rush build) and deploy (rush host) my PR
• I have connected the issues(s) to this PR
• 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 created new issue(s) related to the outcome of this PR is needed
• I have made corresponding changes to the documentation
• 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

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This change is 

[jolevesq]

Reviewed 9 of 9 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @DamonU2)

[Alex-NRCan]

Reviewed 8 of 9 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved