build: enable subproject-based build

* Move existing phosphor-logging.wrap to the subprojects directory.
* Add wrap files for all openbmc dependencies.
* Fix up meson.build files to utilize subproject dependencies and follow
  Meson conventions for dependency naming.
* Ensure wrap files are not ignored by .gitignore.

Tested: Built on a typical Linux development system and 'ninja test'
        passed.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I167911f045ee1f27cc69bcba7be185762844a030
diff --git a/subprojects/phosphor-logging.wrap b/subprojects/phosphor-logging.wrap
new file mode 100644
index 0000000..71eee8b
--- /dev/null
+++ b/subprojects/phosphor-logging.wrap
@@ -0,0 +1,6 @@
+[wrap-git]
+url = https://github.com/openbmc/phosphor-logging.git
+revision = HEAD
+
+[provide]
+phosphor-logging = phosphor_logging_dep