* Switch Umpire to CMakeCachedPackage
* Fix missing import
* Correct tests option in Umpire
* Switch RAJA to CachedCMakePackage
* Convert CHAI to CachedCMakePackage
* Corrections in RAJA
* Patches in Umpire & RAJA for BLT target export
* Fixup style
* Fixup incorrect use of cmake_cache_string
fixes#25992
Currently the bootstrapping process may need a compiler.
When bootstrapping from sources the need is obvious, while
when bootstrapping from binaries it's currently needed in
case patchelf is not on the system (since it will be then
bootstrapped from sources).
Before this PR we were searching for compilers as the
first operation, in case they were not declared in
the configuration. This fails in case we start
bootstrapping from within an environment.
The fix is to defer the search until we have swapped
configuration.
While debugging #24508, I noticed that we call `basename` in `cc`. The
same can be achieved by using Bash's parameter expansion, saving one
external process per call.
Parameter expansion cannot replace basename for directories in some
cases, but is guaranteed to work for executables.
Git 2.24 introduced a feature flag for repositories with many files, see:
https://github.blog/2019-11-03-highlights-from-git-2-24/#feature-macros
Since Spack's Git repository contains roughly 8,500 files, it can be
worthwhile to enable this, especially on slow file systems such as NFS:
```
$ hyperfine --warmup 3 'cd spack-default; git status' 'cd spack-manyfiles; git status'
Benchmark #1: cd spack-default; git status
Time (mean ± σ): 3.388 s ± 0.095 s [User: 256.2 ms, System: 625.8 ms]
Range (min … max): 3.168 s … 3.535 s 10 runs
Benchmark #2: cd spack-manyfiles; git status
Time (mean ± σ): 168.7 ms ± 10.9 ms [User: 98.6 ms, System: 126.1 ms]
Range (min … max): 144.8 ms … 188.0 ms 19 runs
Summary
'cd spack-manyfiles; git status' ran
20.09 ± 1.42 times faster than 'cd spack-default; git status'
```
