Fix TR unit tests.

Make new tests actually run as part of the unit tests.
Make them not broken.
Fix broken package dependencies.
Add list of confirmed speakers to RacketCon page.
Add links to speaker web pages. Formatting.
fix typo and add test suite for invariant-assertion
raco pkg catalog-show: improve error for bad catalog
raco pkg catalog-archive: fix handling of source with no checksum
raco pkg: fix treatmennt of "file://" package sources

A "file://" prefix on a package source needs to be consistently
removed. The new `package-source->path` function does that, so it
should be used to convert a package source to a filesystem path.
fix `collection-file-path` & related for binary package installation

Binary package installation failed in the case of collection
splicing, because module-name resolution via `collection-file-path`
did not check for compiled files along hte search path of
registered collection directories.
rackunit/docs-complete: move to the "racket-index" package

Modules are not supposed to move to different packages, anymore, so
I'm breaking a rule. The problem is that having `rackunit/docs-complete`
in "scribble-lib" made "scribble-lib" depend on "racket-index", and
that's an undesirable dependency. (Installing Scribble shouldn't
force you to have Racket documentation.) I should have noticed
the problem when I moved `setup/xref` to "racket-index", but I missed
it.

As far as I can tell, there's only one package on pkgs.racket-lang.org
that isn't in the main repository and uses `rackunit/docs-index`. The
package doesn't correctly declare its dependencies, anyway.
net/url: add `relative-path->relative-url-string`
pkg/lib: more fixes to handling of relative package sources in catalogs

Relative paths in a catalog should be treated as relative URLs, not
relative paths.
make site: use relative paths in the pkg catalog for a site
raco setup: fix dependency checking and PLTCOMPILEDROOTS

Closes PR 14537
raco setup: fix documentation rebuild for PLTCOMPILEDROOTS
raco pkg: fix conflict checking for PLTCOMPILEDROOTS

The fix is for a corner case that is unlikely to show up,
but the repaired code is simpler.
fix typo in Windows "build.bat"
Win64: fix JIT floating-point constant

Repairs commit 71591a62a4 for Win64, where `long` != `intptr_t`
raco pkg: fix doc typo
optimizer report use-before-definition check at debug level

It's too common and noisy as a warning.
change `collection-file-path` to check for compiled by default for ".rkt"