cmake_file_api: New project command

Projects can use the new command to request file API replies for the current
run. No query files are generated, the query is tracked internally. Replies are
created in the file system at generation time in the usual way.

Fixes: #24951

Tests/RunCMake/FileAPI/ProjectQueryBad.cmake

@@ -0,0 +1,42 @@
+# All of these should fail. Execution does continue though, so we should see
+# the error output from each one. There is no observable effect of the command
+# during the configure phase, so it isn't critical to end processing on the
+# first failure. Allowing execution to proceed may allow the project to see
+# other potential errors before ultimately halting. That behavior is generally
+# desirable, and the multiple failing calls here will confirm that we retain
+# that behavior.
+
+message(NOTICE "Non-query check")
+cmake_file_api(NOT_A_QUERY)
+
+message(NOTICE "Invalid API version checks")
+cmake_file_api(QUERY API_VERSION 2)
+cmake_file_api(QUERY API_VERSION nah)
+
+message(NOTICE "Invalid version numbers check")
+cmake_file_api(
+  QUERY
+  API_VERSION 1
+  CODEMODEL nope
+  CACHE -2
+  CMAKEFILES .8
+  TOOLCHAINS 2 0.1
+)
+
+message(NOTICE "Requested versions too high check")
+cmake_file_api(
+  QUERY
+  API_VERSION 1
+  CODEMODEL 3
+  CACHE 3
+  CMAKEFILES 2
+  TOOLCHAINS 1.1
+)
+
+message(NOTICE "Requested versions too low check")
+cmake_file_api(
+  QUERY
+  API_VERSION 1
+  CODEMODEL 1
+  CACHE 1
+)