Delay CPF merge activation until all config changes have been made during unmap and enable commands; also fix some mapped IPM issues

[isc-dchui]

Fixes #1001
Fixes #1052

This is what the intro message for a namespace with mapped IPM now looks like

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|| Welcome to the Package Manager Shell (ZPM). Version: 0.10.6-SNAPSHOT (mapped from namespace 'USER')          ||
|| Enter q/quit to exit the shell. Enter ?/help to view available commands                                      ||
|| Current registry https://pm.community.intersystems.com/                                                      ||
|| System Mode: <unset>                                                                                         ||
|| Mirror Status: NOTINIT                                                                                       ||
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