Migrate app-server config to default.yaml - based config via configmgr

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Currently, app-server determines its config via:

• zowe.yaml which the user actually edited
• env vars
• cli args
• convert-env.sh which sets things via sensing conditions on the env vars
• zluxArgs.js hardcoded defaults

in particular, convert-env.sh has a lot of weird and complicated conditions with plenty of backward compatibility.

zss had similarly complexity and has been reduced to just

• zowe.yaml
• defaults.yaml packaged within zss

we should

• cut out convert-env.sh
• remove zluxArgs.js hardcoded defaults
• stop reading env vars directly within the zlux-server-framework code
• add a defaults.yaml which has allll the conditionals we need to do the same sorts of actions found in those, except REMOVE v1 compatibility because it does not make sense in the v2 codebase!

here's how zss does conditionals in defaults.yaml
https://github.com/zowe/zss/blob/v2.x/staging/defaults.yaml

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This was complete in v2.10