Fix typos in code comments and string literals

[leopardracer]

This pull request fixes several typos found in the codebase:

1. Fixed spelling of "initialization" in database/ffldb/whitebox_test.go
2. Standardized capitalization of "register" in database/ffldb/driver.go
3. Fixed capitalization of "transaction" in database/ffldb/interface_test.go
4. Standardized formatting in blockchain/indexers/utreexoproofindex.go

These changes are purely cosmetic and do not affect functionality.

[kcalvinalvin]

Could you merge this into a single commit?

[leopardracer]

Could you merge this into a single commit?

ready