Add support for templates in tt config.

To support more flexible environment configuration and convenient tarantool 3.0 integration, it would be nice to support templates in tt config file. Examples, local:

tt:
  app:
    run_dir: "var/run/{{ instance_name }}"
    log_dir: "var/log/{{ instance_name }}"
    wal_dir: "var/lib/{{ instance_name }}"
    memtx_dir: "var/lib/{{ instance_name }}"
    vinyl_dir: "var/lib/{{ instance_name }}"

Pid file location will be <instances_enabled>/app/var/run/master/tarantool.control
Global (absolute paths):

tt:
  app:
    run_dir: "/var/run/tarantool/{{ app_name}}/{{ instance_name }}"
    log_dir: "/var/log/tarantool{{ app_name}}/{{ instance_name }}"
    wal_dir: "/var/lib/tarantool/{{ app_name}}/{{ instance_name }}"
    memtx_dir: "/var/lib/tarantool/{{ app_name}}/{{ instance_name }}"
    vinyl_dir: "/var/lib/tarantool/{{ app_name}}/{{ instance_name }}"

Pid file location will be "/var/run/tarantool/app/master/tarantool.control"
After adding the templates support, all the logic for appending app/instance name suffixes to paths must be removed.
Tarantoolctl layout can be represented by the following paths:

tt:
  app:
    run_dir: "var/run/"
    log_dir: "var/log/"
    wal_dir: "var/lib/{{ instance_name }}"
    memtx_dir: "var/lib/{{ instance_name }}"
    vinyl_dir: "var/lib/{{ instance_name }}"

cartridge sub-command code must be updated to support instances navigation with updated layout. Currently it accepts a run dir path and makes an assumption about the file tree structure in this directory. tt cartridge sub-commands must be able to work with any layout specified by a user in tt.yaml config.

Start by tracing tt.yaml path configuration and the tt cartridge sub-command code that navigates instances from a run directory. Compare the local, global, and Tarantoolctl layouts described in the issue. Done means templates work for the listed paths and cartridge sub-commands work with any user-specified layout.