fix(geocore): refactor layerOrder to keep geocore in proper order

[DamonU2]

Closes #1852

Description

Layer order now maintains geocore layers in the proper location when they switch to the actual layer type.

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/all-layers.html
https://damonu2.github.io/geoview/geocore.html

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 

[Alex-NRCan]

Reviewed 11 of 11 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @jolevesq)

[jolevesq]

Reviewed 3 of 10 files at r2, all commit messages.
Reviewable status: 7 of 14 files reviewed, all discussions resolved (waiting on @Alex-NRCan)

[jolevesq]

Reviewable status: 7 of 14 files reviewed, all discussions resolved (waiting on @Alex-NRCan)

[jolevesq]

Reviewed 1 of 10 files at r2.
Reviewable status: 8 of 14 files reviewed, all discussions resolved (waiting on @Alex-NRCan)

[jolevesq]

Reviewed 3 of 11 files at r1.
Reviewable status: 8 of 14 files reviewed, all discussions resolved (waiting on @Alex-NRCan)

[jolevesq]

Reviewed 1 of 11 files at r1, 6 of 10 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @DamonU2)

[jolevesq]

Reviewed 11 of 11 files at r3, 5 of 5 files at r4, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @DamonU2)