Epochs::default()uses block height 0 as the first block height of the first epoch

[james-chf]

In our Epochs struct, we should ensure we are returning BlockHeight(1) as the first block height of the first epoch, rather than BlockHeight(0). This may work for tests but BlockHeight(0) is not a realistic block height for real Tendermint chains.

namada/shared/src/types/storage.rs

Lines 621 to 630 in d1a06a2

	impl Default for Epochs {
	/// Initialize predecessor epochs, assuming starting on the epoch 0 and
	/// block height 0.
	fn default() -> Self {
	Self {
	first_known_epoch: Epoch::default(),
	first_block_heights: vec![BlockHeight::default()],
	}
	}
	}

Related: #377

[tzemanovic]

duplicate of #648