Split "kmerseek search" into "search-create-query-sketch", "search-get-query-kmers", "search-do-search", "search-get-matching-kmers"

[olgabot]

Similar to #7, this would split up kmerseek search from the convenient one-liner for the CLI, into at least 6 different subcommands. These commands would call separate Sourmash/Branchwater CLIs and/or custom code:

1. search-create-query-sketch: sourmash scripts manysketch (uses as many CPUs as available, low-medium memory)
2. search-get-query-kmers: sourmash sig kmers (takes a long time, but only 1 CPU and low memory)
3. search-do-search: sourmash scripts manysearch (uses as many CPUs as available, low-medium memory)
4. search-get-matching-kmers: Custom code, most likely kmerseek.search.KmerseekResults.join_query_target_kmers(), KmerseekResults.join_results_kmers(), KmerseekResults.stitch_kmers_per_gene()
5. search-get-uniprot-domains: [TODO: First need to implement the Uniprot domain search in the first place] Get Uniprot domains from overlapping regions found in k-mers #6
6. search-output-per-gene-results: Custom code, most likely kmerseek.search.KmerseekResults.show_results_per_gene()

Notice that each command is named search-VERB-something -- I like this style for clarity. Also taking suggestions on naming, the hardest problem!