`show_shared` parameter of `get_runs` needs to have a "do not modify" option

[alahiff]

The show_shared parameter of get_runs means that it's not possible to copy filters from the UI and directly use them in get_runs if runs are shared. This was found while working on the noSim server.

There should be a None option added to show_shared, in addition to the existing True and False. When None is used the client shouldn't secretly modify the filters provided by the user and just use the provided filters as-is.

[wk9874]

setting this setting to True will not edit the filters as described above, so will just change the default setting to True :)

[kzscisoft]

@wk9874 did this work?