adds flow button back on a no-gauge page if in edit mode.

[ryangroth5]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

• Adds edit flows button if no gauge is associated with a river

• What is the current behavior? (You can also link to an open issue here)

• no way to edit flows if no gauge already exists

• What is the new behavior (if this is a feature change)?

• edit flows buttons shows up on form in edit mode

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

• no

• Other information:

• no