Most of this migration was performed automatically with `zig fmt`. There
were a few exceptions which I had to manually fix:
* `@alignCast` and `@addrSpaceCast` cannot be automatically rewritten
* `@truncate`'s fixup is incorrect for vectors
* Test cases are not formatted, and their error locations change
Tests that only reference decls for the purpose of analyzing more tests
should be unnamed, otherwise trying to filter for just a referenced test
can become impossible depending on the names.
std.crypto.ecc: add support for the secp256k1 curve
Usage of the secp256k1 elliptic curve recently grew exponentially,
since this is the curve used by Bitcoin and other popular blockchains
such as Ethereum.
With this, Zig has support for all the widely deployed elliptic curves
today.
