Add filter parameter support

$filter is a parameter documented in the Redfish specification, section
7.3.4.  It defines a mechanism for filtering arbitrary collections of
parameters based on a set of arbitrary language expressions.

From the specification, it supports the following language operators:

() Precedence grouping operator.
(Status/State eq 'Enabled' and Status/Health eq 'OK')
or SystemType eq 'Physical'

and Logical and operator.
ProcessorSummary/Count eq 2 and MemorySummary/TotalSystemMemoryGiB gt 64

eq Equal comparison operator.
ProcessorSummary/Count eq 2

ge Greater than or equal to comparison operator.
ProcessorSummary/Count ge 2

gt Great than comparison operator.
ProcessorSummary/Count gt 2

le Less than or equal to comparison operator
 MemorySummary/TotalSystemMemoryGiB le 64

lt Less than comparison operator.
MemorySummary/TotalSystemMemoryGiB lt 64

ne Not equal comparison operator.
SystemType ne 'Physical'

not Logical negation operator.
not (ProcessorSummary/Count eq 2)

or Logical or operator.
ProcessorSummary/Count eq 2 or ProcessorSummary/Count eq 4

Support for these operators have been added in previous commits.  This
commit enables them behind the insecure-enable-redfish-query meson
option.  This is an arbitrary language, so the likelihood there's some
improper implementation in the patch is high.  This gives folks the
ability to test it.

Tested:
Lots of unit tests included in this patch.

Functionally tested the basic operators:
```
GET /redfish/v1/Managers/bmc/LogServices/Journal/Entries?\$filter=EntryType+eq+'Oem'
GET /redfish/v1/Managers/bmc/LogServices/Journal/Entries?\$filter=EntryType+ne+'Oem'
```

Function as expected, producing multiple results or no results
respectively.

GET /redfish/v1 reports "FilterQuery": true

Redfish service validator passes.

Change-Id: Id568acc5dcfce868af12da5ee16c4f0caae8060a
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/meson.build b/meson.build
index 6ca861d..63fed9e 100644
--- a/meson.build
+++ b/meson.build
@@ -72,6 +72,7 @@
         '-Wformat=2',
         '-Wno-c++98-compat-pedantic',
         '-Wno-c++98-compat',
+        '-Wno-c++20-extensions',
         '-Wno-documentation-unknown-command',
         '-Wno-documentation',
         '-Wno-exit-time-destructors',
@@ -332,6 +333,7 @@
 
     'redfish-core/src/error_messages.cpp',
     # Begin large files, should be at the beginning
+    'redfish-core/src/filter_expr_executor.cpp',
     'redfish-core/src/filter_expr_printer.cpp',
     'redfish-core/src/redfish.cpp',
     'redfish-core/src/registries.cpp',
@@ -393,6 +395,7 @@
     'test/include/ssl_key_handler_test.cpp',
     'test/include/str_utility_test.cpp',
     'test/redfish-core/include/privileges_test.cpp',
+    'test/redfish-core/include/filter_expr_executor_test.cpp',
     'test/redfish-core/include/filter_expr_parser_test.cpp',
     'test/redfish-core/include/redfish_aggregator_test.cpp',
     'test/redfish-core/include/registries_test.cpp',