GIT: Page path should be in lowercase, otherwise it cannot be handled by some OSes

[akaRem]

Describe the bug
When git storage is enabled, 2 files with the same name may be commited which cannot be handled by some OSes which ignore letters case in file paths (macOS, windows):

➜  git clone git@ssh.gitlab.my.domain.com:my/wiki.git
Cloning into 'wiki'...
remote: Enumerating objects: 268, done.
remote: Counting objects: 100% (268/268), done.
remote: Compressing objects: 100% (192/192), done.
remote: Total 268 (delta 60), reused 251 (delta 51)
Receiving objects: 100% (268/268), 3.72 MiB | 4.18 MiB/s, done.
Resolving deltas: 100% (60/60), done.
warning: the following paths have collided (e.g. case-sensitive paths
on a case-insensitive filesystem) and only one from the same
colliding group is in the working tree:
  'docs/Components.md'
  'docs/components.md'

To Reproduce
Steps to reproduce the behavior:
0. deploy on linux host/docker container

1. Enable and configure git
2. create page w/ path docs/Components
3. create page w/ path docs/components
4. clone repo
5. repo can not be cloned

Expected behavior
It should be impossible to type any path that cannot be handled by OS fs or produce any kind of conflict (no special characters, utf ext ranges, uppercased letters, emogi, spaces, etc)

Screenshots
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Host Info (please complete the following information):

• OS: macOS, docker/linux
• Wiki.js version: 2.0.12

Additional context
Add any other context about the problem here.