Specialize checkindex for an AbstractFill index

[jishnub]

checkindex for an AbstractFill index was being pirated by InfiniteArrays.jl, and incompletely, since the Bool array behaves differently from an Int one. This PR moves the method to this package, where it belongs.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (877375f) to head (fd5db92).
⚠️ Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
src/FillArrays.jl	0.00%	2 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (877375f) and HEAD (fd5db92). Click for more details.

HEAD has 10 uploads less than BASE

Flag	BASE (877375f)	HEAD (fd5db92)
	18	8

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #411       +/-   ##
==========================================
- Coverage   99.48%   0.00%   -99.49%     
==========================================
  Files           8       8               
  Lines        1157    1161        +4     
==========================================
- Hits         1151       0     -1151     
- Misses          6    1161     +1155     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[jishnub]

The test failures in InfiniteArrays.jl and InfiniteLinearAlgebra.jl are expected because of this type-piracy. Setting persistent_tasks=false in the Aqua checks gets the tests to pass.

[jishnub]

Gentle bump

[jishnub]

Gentle bump