New file/workspace selector widget

[mantid-builder]

Original Reporter: Samuel Jackson

Both the IDA and C2E interface make use of a combination of WorkspaceSelectors and MWRunsFiles to get the names of either a workspace or a file to work with. This pattern could benefit from become a separate Mantid widget to prevent code repetition and could easily be used elsewhere in Mantid. This is especially true as several upcoming tickets will use the exact same pattern several times over.

[mantid-builder]

This issue was originally trac ticket 7681