Enable support for Aviso/Mirror attributes

[FussyDuck]

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1 out of 2 committers have signed the CLA.

:white_check_mark: marcosbento
:x: sandorkertesz
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 65.59675% with 761 lines in your changes missing coverage. Please review.

Project coverage is 47.13%. Comparing base (e7cd7ea) to head (655043e).

Files	Patch %	Lines
Viewer/ecflowUI/src/NodeViewDelegate.cpp	0.00%	160 Missing :warning:
libs/node/src/ecflow/node/AvisoAttr.cpp	8.69%	84 Missing :warning:
Viewer/ecflowUI/src/VAvisoAttr.cpp	0.00%	65 Missing :warning:
Viewer/ecflowUI/src/VMirrorAttr.cpp	0.00%	58 Missing :warning:
libs/node/src/ecflow/node/MirrorAttr.cpp	18.84%	56 Missing :warning:
libs/base/src/ecflow/base/cts/user/AlterCmd.cpp	0.00%	32 Missing :warning:
libs/node/src/ecflow/node/NodeMemento.cpp	15.15%	28 Missing :warning:
libs/node/src/ecflow/node/NodeChange.cpp	54.23%	27 Missing :warning:
libs/node/src/ecflow/node/NodeDelete.cpp	63.51%	27 Missing :warning:
...s/service/src/ecflow/service/aviso/etcd/Client.cpp	45.71%	19 Missing :warning:
... and 32 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #102 +/- ## =========================================== + Coverage 46.73% 47.13% +0.39% =========================================== Files 1132 1179 +47 Lines 91159 93187 +2028 Branches 14564 14732 +168 =========================================== + Hits 42604 43923 +1319 - Misses 48555 49264 +709 ```

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