Move database directory to data_dir

[looowizz]

Some people use different hard drives for heavy data and app install directories (https://doc.yunohost.org/en/external_storage#1-identify-directories-to)

• Add upgrade strategy to move data from install_dir to data_dir
• Change install script
• Add backup & restore directories

[looowizz]

See this config line

conduwuit_ynh/conf/conduwuit.toml

Line 80 in 3195977

database_path = "__INSTALL_DIR__/db"