clang-format: Specify lambda formatting

Do so in accordance with existing community practice:

1. https://github.com/openbmc/bmcweb/blob/5b5574ace856c7f787528ab8f5e5352a90f2a6cb/.clang-format#L84
2. https://github.com/openbmc/dbus-sensors/blob/6747eba5e06ce8f7b407193410aa7d04eb5b833c/.clang-format#L53

Change-Id: Ic89424f510578622c1ac5627e28b0293e4da7e07
Signed-off-by: Andrew Jeffery <[email protected]>

Author: amboar

style/cpp/.clang-format

@@ -79,6 +79,7 @@ IndentRequiresClause: true
 IndentWidth:     4
 IndentWrappedFunctionNames: true
 KeepEmptyLinesAtTheStartOfBlocks: false
+LambdaBodyIndentation: OuterScope
 MacroBlockBegin: ''
 MacroBlockEnd:   ''
 MaxEmptyLinesToKeep: 1