Change how goodkey.KeyPolicy keeps track of allowed RSA and ECDSA key
sizes, to make it slightly more flexible while still retaining the very
locked-down allowlist of only 6 acceptable key sizes (RSA 2048, 3076,
and 4092, and ECDSA P256, P384, and P521). Add a new constructor which
takes in a collection of allowed key sizes, so that users of the goodkey
package can customize which keys they accept. Rename the existing
constructor to make it clear that it uses hardcoded default values.
With these new constructors available, make all of the goodkey.KeyPolicy
member fields private, so that a KeyPolicy can only be built via these
constructors.
8545ea8364