Feature: [supertask runtime estimation] support .hcchr and .hcmask files

[SherlockNL]

Recently a pull request has been opened for supertask runtime estimation on the supertask detail page: #696

For -a3 attacks, the hashcat built-in charsets (?l?u?d?h?H?s?a?b) are all supported, including custom charsets consisting of these built-in charsets such as "-1 ?u?l?d".

However, custom hashcat charset files (file extension: .hcchr) and hashcat mask files (file extension: .hcmask) are not yet supported, and might result in a wrong estimate due to the line count of such a file being taken into account anyway.

It would be great to be able to estimate runtimes for tasks with custom charset files or mask files. This might be a little difficult to add. This issue is more challenging to solve than https://github.com/s3inlc/hashtopolis/issues/708