add uid/gid modification to match hosts uid/gid

[edgd1er]

When using mounted volumes, container uid/gid have to match hosts uid/gid in order to have rights on the files.

Description

set pihole uid/gid according to env values PIHOLE_UID/PIHOLE_GID

this feature was already present in previous pihole versions.

Motivation and Context

docker-pi-hole-pihole-1 | 2023-07-26 08:07:12.945 [177M] WARNING: chmod(/etc/pihole/pihole-FTL.db, 436): chmod() failed: Operation not permitted

How Has This Been Tested?

When setting uid/gid, no more warning are displayed in the container logs.

Types of changes

• 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)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[PromoFaux]

Sorry, I actually already had this done, just forgot to push and PR (now here: #1403)

Similar change, but I would rather it was just in start.sh - no need for a reusable function