Implement stacks-block-height and tenure-height

[obycode]

SIP-021 specifies the following updates to Clarity:

The protocol described in this document would have Stacks blocks occur at a much greater frequency than in the past. Many contracts rely on the block-height primitive to approximate a time assuming that a block takes, on average, 10 minutes. To release faster blocks while preserving the functionality of existing contracts that make this block frequency assumption, this proposal calls for a new version of Clarity, version 3, which includes the following changes.

A new Clarity global variable stacks-block-height will be introduced, which evaluates to the Stacks block height.
A new Clarity global variable tenure-height will be introduced, which evaluates to the number of tenures that have passed. When the Nakamoto block-processing starts, this will be equal to the chain length.
The Clarity global variable block-height will continue to be supported in existing Clarity 1 and Clarity 2 contracts by returning the same value as tenure-height. Usage of block-height in a Clarity 3+ contract will trigger an analysis error.

These changes will be implemented in the interpreter in stacks-network/stacks-core#3943 and also need to be implemented in the clarity-wasm runtime.