Layout Scene: Reorganize variables

[gtk-grafana]

With line filters being moved into the variables in the header, we've got quite a lot going on when queries get more complex:

While at least the variables are in the same order as the logQL query now, I think we should do a better job illustrating that the order of operations is a function of how loki will find the logs you are searching for.

Also things look "messy", and we could do a better job collapsing and expanding variables so the header doesn't take up so much vertical space.

Some things we discussed:

• Move labels "combobox" on it's own line
• Move the feedback link to the left of the time picker
• put datasource and datapicker/refresh on the same line.
• Adding borders and indentiation to better separate each variable type
• Unifying styles, we've got "pill" style for the combobox and patterns, but "input" style on the fields and the line filters.
• Collapsing patterns

Some things we haven't discussed:

• Drag and drop all variables to change the filter order (within each row, users shouldn't be able to put a line filter or field variable before a metadata variable)

CC @zizzpudding