feat: add drop key functionality (#6)

Currently, the `Table.Drop()` function is deprecated because it is not implemented yet. Let's add that functionality.

- Adds true drop functionality to the table, through `Table.Drop()`.
- Adds tests for functionality.
- Rewrites fuzz test using `go_fuzz_utils`, to test arbitrary usage patterns.
- Rewrite `bucket` to allow a capacity of zero.
- Rename `Table.Capacity()` to `Table.TotalCapacity()`, to reflect to different between the capacity of the buckets vs. the whole table.
- Enforce 100% mutation test coverage.

Reviewed-on: #6
Co-authored-by: M.V. Hutz <git@maximhutz.me>
Co-committed-by: M.V. Hutz <git@maximhutz.me>

go.mod

@@ -4,8 +4,11 @@ go 1.25.6
 
 require github.com/stretchr/testify v1.11.1
 
+require github.com/kr/pretty v0.3.1 // indirect
+
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/trailofbits/go-fuzz-utils v0.0.0-20260318143407-0907cafe7589
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )