search configuration hit part 1

[rrahn]

Description

Following the design decissions at seqan/seqan3#1580 restructure the configuration mode.
Here are the design decisions: https://docs.google.com/document/d/1Lv7zxtDUgAeHGcnJ6IWFzgIbJ6rFJlUt2linAOjlIBg/edit#heading=h.mfoteev73s87

See following code example:

//usage: 

seqan3::search_cfg::hit_all_best

// construction - no construction since it is a tag

seqan3::search_cfg::hit_all_best
// this is an instance of seqan3::search_cfg::hit_all_best_tag     

//access by seqan::get:

auto && var = seqan3::get<seqan3::search_cfg::hit_all_best_tag>(config);

//check if present:

constexpr bool has_hit_all_best_tag = config_t::template exists<seqan3::search_cfg::detail::hit_all_best_tag>();

The other configs are analoge, except for strata which captures an argument:

// construction

seqan3::search_cfg::hit_strata hit_strata(5)    

// later access and set

hit_strata.stratum = 5;    

// access by seqan::get:

auto && hit_strata = seqan3::get<seqan3::search_cfg::hit_strata>(config);
hit_strata.stratum = 5;

// check if present:

constexpr bool has_hit_strata = config_t::template exists<seqan3::search_cfg::detail::hit_strata>();

Acceptance Criteria

• The seqan3::search_cfg::mode{seqan3::search_cfg::all} is a top level configuration element seqan3::search_cfg::hit_all
• The seqan3::search_cfg::mode{seqan3::search_cfg::all_best} is a top level configuration element seqan3::search_cfg::hit_all_best
• The seqan3::search_cfg::mode{seqan3::search_cfg::best} is a top level configuration element seqan3::search_cfg::hit_best
• The seqan3::search_cfg::mode{seqan3::search_cfg::strate{3}} is a top level configuration element seqan3::search_cfg::hit_strata{3}
• Combining any of these with each other will cause a static assertion

Tasks

• Add seqan3::search_cfg::hit_all configuration mode with documentation
• Add seqan3::search_cfg::hit_all_best configuration mode with documentation
• Add seqan3::search_cfg::hit_best configuration mode with documentation
• Add seqan3::search_cfg::hit_strata configuration mode with documentation
• Write summary documentation on the seqan3/search/configuration/all.hpp module page.

Definition of Done

• Implementation and design approved
• Unit tests pass
• Test coverage = 100%
• Microbenchmarks added and/or affected microbenchmarks < 5% performance drop
• API documentation added
• Tutorial/teaching material added
• Test suite compiles in less than 30 seconds (on travis)
• Changelog entry added