New subcommand: spack bootstrap status (#28004)

This command pokes the environment, Python interpreter
and bootstrap store to check if dependencies needed by
Spack are available.

If any are missing, it shows a comprehensible message.

share/spack/qa/run-unit-tests

@@ -38,6 +38,7 @@ bin/spack help -a
 
 # Profile and print top 20 lines for a simple call to spack spec
 spack -p --lines 20 spec mpileaks%gcc ^dyninst@10.0.0 ^elfutils@0.170
+$coverage_run $(which spack) bootstrap status --dev --optional
 
 #-----------------------------------------------------------
 # Run unit tests with code coverage

share/spack/spack-completion.bash

@@ -434,10 +434,14 @@ _spack_bootstrap() {
     then
         SPACK_COMPREPLY="-h --help"
     else
-        SPACK_COMPREPLY="enable disable reset root list trust untrust"
+        SPACK_COMPREPLY="status enable disable reset root list trust untrust"
     fi
 }
 
+_spack_bootstrap_status() {
+    SPACK_COMPREPLY="-h --help --optional --dev"
+}
+
 _spack_bootstrap_enable() {
     SPACK_COMPREPLY="-h --help --scope"
 }