fix(main/sftpgo): Relocate data path to fix running server

[Biswa96]

• Fixes How can i use SFTPGo? #23036

[Biswa96]

sftpgo shows the following error when $PREFIX/var/lib/sftpgo directory is absent.

$ sftpgo serve
INF creating initial database schema, version 28
WRN Unable to initialize data provider: unable to open database file: no such file or directory
ERR error initializing data provider: unable to open database file: no such file or directory

After adding that directory in build script, sftpgo shows the following error due to not finding the template directory in sftpgo.json file.

$ sftpgo serve
INF creating initial database schema, version 28
DBG Data provider successfully initialized
INF updating database schema version: 28 -> 29
ERR error loading required template: open templates/email/reset-password.html: no such file or directory
ERR Try setting the absolute templates path in your configuration file or specifying the config directory adding the `-c` flag to the serve options. For example: sftpgo serve -c "<path to dir containing the default config file and templates directory>"

After fixing the sftpgo.json, it now works.