Dec Spec: Support the syntax of the structure array for structure PCD

In V2, update array style to more than one dimension array.
In V3, Update Pcd Field value assignment with array index.
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=1292

1. Support the syntax of the structure array for structure PCD
2. Add the syntax to initialize structure PCD with C style value

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liming Gao <liming.gao@intel.com>
Cc: Bob Feng <bob.c.feng@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>

Author: lgao4

3_edk_ii_dec_file_format/310_pcd_sections.md

@@ -125,7 +125,7 @@ PCDs listed in `PcdsFeatureFlag` sections must only be listed in
 <PcdUint32>       ::= {<NumValUint32>} {<Expression>} <FS> "UINT32"
 <Pcd64>           ::= <PcdName> <FS> <PcdUint64> <FS> <Token> <CbOrEol>
 <PcdUint64>       ::= {<NumValUint64>} {<Expression>} <FS> "UINT64"
-<PcdStruct>       ::= <PcdName> <FS> <PtrVal> <FS> <CName> <FS> <Token> "{" <EOL>
+<PcdStruct>       ::= <PcdName> <FS> <PtrVal> <FS> {<CName>} {<CArrayName>} <FS> <Token> "{" <EOL>
                       <TS> <PcdStructHF>
                       <TS> <PcdStructPKGs> "}" <CbOrEol>
 <PcdStructHF>     ::= "<HeaderFile>" <EOL> <PcdStructFile>

3_edk_ii_dec_file_format/32_package_declaration_dec_definitions.md

@@ -87,6 +87,7 @@ DEC file (for example, `<Expression>` statements are not permitted).
 <NonDigit>            ::= (a-zA-Z_)
 <Identifier>          ::= <NonDigit> <Chars>*
 <CName>               ::= <Identifier> # A valid C variable name.
+<CArrayName>          ::= <Identifier>["["[<Number>]"]"]+ # A valid C variable array name.
 <AsciiChars>          ::= (0x21 - 0x7E)
 <CChars>              ::= [{0x21} {(0x23 - 0x26)} {(0x28 - 0x5B)}
                           {(0x5D - 0x7E)} {<EscapeSequence>}]*
@@ -166,7 +167,7 @@ DEC file (for example, `<Expression>` statements are not permitted).
 <MACRO>               ::= (A-Z)(A-Z0-9_)*
 <MACROVAL>            ::= "$(" <MACRO> ")"
 <PcdName>             ::= <TokenSpaceGuidCName> "." <PcdCName>
-<PcdFieldName>        ::= <TokenSpaceGuidCName> "." <PcdCName> "." <Field>
+<PcdFieldName>        ::= <TokenSpaceGuidCName> "." <PcdCName> ["["<Number>"]"]* "." <Field>
 <PcdCName>            ::= <CName>
 <TokenSpaceGuidCName> ::= <CName>
 <PcdFieldEntry>       ::= <PcdFieldName> <FS> <PcdFieldValue> <EOL>
@@ -208,14 +209,15 @@ DEC file (for example, `<Expression>` statements are not permitted).
 <StringVal>           ::= {<UnicodeString>} {<CString>} {<Array>}
 <Array>               ::= "{" {<Array>} {[<Lable>] <ArrayVal> 
                            [<CommaSpace> [<Lable>] <ArrayVal>]* } "}"
-<ArrayVal>            ::= {<Num8Array>} {<GuidStr>} {<DevicePath>} 
+<ArrayVal>            ::= {<Num8Array>} {<GuidStr>} {<DevicePath>} {<CodeStr>}
 <NonNumType>          ::= {<BoolVal>}{<UnicodeString>} {<CString>}
                           {<Offset>} {<UintMac>}
 <Num8Array>           ::= {<NonNumType>} {<ShortNum>} {<UINT8>}
 <Num16Array>          ::= {<NonNumType>} {<IntNum>} {<UINT16>}
 <Num32Array>          ::= {<NonNumType>} {<LongNum>} {<UINT32>}
 <Num64Array>          ::= {<NonNumType>} {<LongLongNum>} {<UINT64>}
 <GuidStr>             ::= "GUID(" <GuidVal> ")"
+<CodeStr>             ::= "CODE(" <CData> ")"
 <GuidVal>             ::= {<DblQuote> <RegistryFormatGUID> <DblQuote>}
                           {<CFormatGUID>} {<CName>}
 <DevicePath>          ::= "DEVICE_PATH(" <DevicePathStr> ")"
@@ -326,6 +328,11 @@ All C data arrays used in PCD value fields must be byte arrays. The C format
 GUID style is a special case that is permitted in some fields that use the
 `<CArray>` nomenclature.
 
+**_CData_**
+
+All C data used in PCD value CODE syntax can be C style value to initialize 
+C structure or Array in C source code.
+
 **_EOL_**
 
 The DOS End Of Line: "0x0D 0x0A" character sequence must be used for all EDK II