Rename effecthash crate to txhash

[hdevalence]

This allows us to put not just the effect hash but also the auth hash and
transaction ID, letting other parts of the source tree reference transaction
IDs without depending on the transaction crate.

[hdevalence]

The "Compile protobuf specs to rust code" fails, but there are no changes locally:

~/c/p/penumbra2 (txhash-crate|✔) $ ./deployments/scripts/protobuf-codegen
Cleaning output dirs...
Pulling proto dependencies from BSR...
~/code/penumbra/penumbra2/proto ~/code/penumbra/penumbra2
Generating golang code...
~/code/penumbra/penumbra2
Generating rust code...
~/code/penumbra/penumbra2/tools/proto-compiler ~/code/penumbra/penumbra2
    Finished dev [unoptimized + debuginfo] target(s) in 0.10s
     Running `target/debug/penumbra-proto-compiler`
root: /Users/hdevalence/code/penumbra/penumbra2/tools/proto-compiler
target_dir: /Users/hdevalence/code/penumbra/penumbra2/tools/proto-compiler/../../crates/proto/src/gen
cnidarium_target_dir: /Users/hdevalence/code/penumbra/penumbra2/tools/proto-compiler/../../crates/cnidarium/src/gen
~/code/penumbra/penumbra2
Finished! Consider running a 'cargo check --release' to confirm builds still work.

Changing the CI workflow to add a git diff to actually show what the changes are results in the entire workflow not running (?).