ENH: add action to filter SampleData[MAGs]

[misialq]

It should be possible to filter by:

• sample metadata (by passing appropriate metadata where sample ID is the index)
• MAG metadata (by passing metadata where feature ID is the index, e.g. BUSCO results)

In the first case, all MAGs from selected samples should be included. In the second case only MAGs matching the criteria should be included, regardless of the sample.

[misialq]

Closed by #169