Fix echo in top-level Makefile for some environments

[ia]

• Please check if the PR fulfills these requirements

• The changes have been tested locally
• There are no breaking changes

• What kind of change does this PR introduce?
  Fix a tiny bug in the top-level Makefile.

• What is the current behavior?
  In some environments (such as docker shell inside alpine 3.16) instead of transforming escape sequences on output respectively, output shows \ts and \n's as is.

• What is the new behavior (if this is a feature change)?
  Replace \ts and \n's by spaces and outputs of new lines explicitly.

• Other information:
  Also I took some liberty to switch WORKDIR for the container. Currently, after you start a docker shell and want to do something with sources, you must manually do extra command (like cd source) to jump into source tree to keep working with scripts & sources. This little change eliminates that by allowing seamlessly keep using exactly the same make / ./scripts/ commands as if you wouldn't left the current IronOS source tree directory on host, i.e.:

• current behavior:

(host) $ ./scripts/deploy.sh
(docker) $ cd source/
(docker) $ make firmware-EN model=TS100

vs

• proposed behavior:

(host) $ ./scripts/deploy.sh
(docker) $ make firmware-EN model=TS100

As far as I understand from official docker documentation, WORKDIR is usually used to avoid providing absolute path for docker file commands such as COPY, but since in IronOS Dockerfile COPY commands are copying files using absolute paths for destinations inside of a container, then such change shouldn't break anything but it will be way much convenient on jumping to the container from source tree.