[MRG] add query info to gather CSV output

[ctb]

Adds query_filename, query_name, query_md5, and query_bp to sourmash gather CSV output.

Fixes #1247 (comment) for gather output.

[codecov]

Codecov Report

Merging #1565 (ef0b7b7) into latest (e2dca11) will increase coverage by 8.11%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           latest    #1565      +/-   ##
==========================================
+ Coverage   81.03%   89.14%   +8.11%     
==========================================
  Files         102       75      -27     
  Lines       10294     6598    -3696     
  Branches     1165     1165              
==========================================
- Hits         8342     5882    -2460     
+ Misses       1744      508    -1236     
  Partials      208      208              

Flag	Coverage Δ
python	89.14% <100.00%> (+<0.01%)	⬆️
rust	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/sourmash/commands.py	86.27% <ø> (ø)
src/sourmash/search.py	96.33% <100.00%> (+0.06%)	⬆️
src/core/src/errors.rs
src/core/src/ffi/hyperloglog.rs
src/core/src/sketch/hyperloglog/mod.rs
src/core/src/index/search.rs
src/core/src/encodings.rs
src/core/src/ffi/mod.rs
src/core/src/index/sbt/mhbt.rs
src/core/src/ffi/utils.rs
... and 19 more

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[ctb]

Ready for review, @bluegenes @taylorreiter @keyabarve @hehouts

[bluegenes]

woohoo, query names!

thanks - looks great :)