### What?
The results when querying orderable collections can be incorrect due to
how the underlying database handles sorting when capitalized letters are
introduced.
### Why?
The original fractional indexing logic uses base 62 characters to
maximize the amount of data per character. This optimization saves a few
characters of text in the database but fails to return accurate results
when mixing uppercase and lowercase characters.
### How?
Instead we can use base 36 values instead (0-9,a-z) so that all
databases handle the sort consistently without needing to introduce
collation or other alternate solutions.
Fixes#12397
37afbe6c04