Add support for new MN Explorer 24.5+

[Nana-EC]

Problem

The MN Explorer went through a rebranding and moved some items around.
This break support with 24.4.0 being the last stable version that doesn't require changes to config setups

Solution

• Update image source to https://github.com/orgs/hiero-ledger/packages?repo_name=hiero-mirror-node-explorer
• Remove use of DOCKER_xxx variables as they are no longer supported
• Support configuration of the networks in public/networks-config.json configuration file
• Explorer some for of automated tests to prevent explorer breaking changes making it through on image updates

Alternatives

No response