[multi-sources-removal] Turn ConnectionsSet into simpler ConnectionWrapper also, SqliteConnectionWrapper becomes a subclass. This is allowed since now ConnectionsSet responsability has been reduced to handling the system source only. This changeset also: * drops useless cnxset_set / check_connection api * deprecates former .source / .connection / container api but it renames neither the session's cnxset attribute, nor the related repository method. Related to #2919300

// This contains template-specific javascript

function filterLog(domid, thresholdLevel) {
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    var action = "hide";
    for (var idx = 0; idx < logLevels.length; idx++){
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        if (level === thresholdLevel){
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        $('#'+domid+' .log' + level)[action]();
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}