GitLab

src:  Made Store keys generic; any fixed-size, serializable type that's Ord + Eq + Hash should work.  Tests in this and imdb-async all pass.

src/lib.rs:  Only instrument Store::get() nad Store::get_index_entry() when "full-instrumentation" is enabled

src/lib.rs:  Load header in Store::new() instead of in Store::is_valid() and Store::get(); this also fixes the issue where closing and reopening a store causes stream_values() to return no results.

Revert ".gitlab-ci.yml:  Revert all the changes from today; need to see if cross-project caching is working this way"

This reverts commit 8e107b26.

.gitlab-ci.yml:  Revert all the changes from today; need to see if cross-project caching is working this way

.gitlab-ci.yml:  Using a CARGO_HOME that's in the CWD is jank; prevents sccache from "sharing" the cache between projects.  This works better; in before_script, move the cached .cargo to /usr/local/cargo, and in after_script, move it back.

.gitlab-ci.yml:  Build first, then clippy - this may reuse some artifacts that are cached from the build

src/lib.rs:  Un-instrument Store::write() and Store::write_infallible(); it was causing compiler panics (type overflows) compiling a downstream crate