Small contract cleanups when reading through the code and configuration

[BigLep]

Small items found or thought of when reviewing filecoin-project/go-f3#823

[BigLep]

Unit tests pass and code coverage is still at 100%:

yarn run v1.22.22
$ /Users/sal/Documents/Code/f3-activation-contract/node_modules/.bin/hardhat coverage

Version

solidity-coverage: v0.8.14

Instrumenting for coverage...

F3Parameters.sol

Compilation:

Nothing to compile
No need to generate any newer typings.

Network Info

HardhatEVM: v2.22.18
network: hardhat

F3Parameters
Deployment
✔ Should set the right expireTime
✔ Should set the right owner
✔ Activation epoch should be max(uint64) and empty params
Parameter updates
✔ Should update activation epoch and manifest data successfully
✔ Should revert if activation epoch is set to a past block
✔ Should revert if activation epoch is less than minActivationHeadroomBlocks ahead of current block
✔ Should revert if update is attempted after activation
✔ Should revert if update is attempted after expiry
✔ Should revert if non-owner attempts to updateActivationInformation

9 passing (63ms)

-------------------|----------|----------|----------|----------|----------------|

File	% Stmts	% Branch	% Funcs	% Lines	Uncovered Lines
contracts/	100	100	100	100
F3Parameters.sol	100	100	100	100
-------------------	----------	----------	----------	----------	----------------
All files	100	100	100	100
-------------------	----------	----------	----------	----------	----------------

Istanbul reports written to ./coverage/ and ./coverage.json
Done in 1.72s.

[Kubuxu]

The alternative is to set it in the .env file.

[Kubuxu]

LGTM