BaseTools: Fix flexible PCD single quote and double quote bugs

BaseTools: Fix flexible PCD single quote and double quote bugs

1.The " and ' inside the string, must use escape character format
  (\", \')
2.'string' and L'string' format in --pcd, it must be double quoted
  first.

  Some examples that to match --pcd format and DSC format
  --pcd                             DSC format
  L"ABC"                            L"ABC"
  "AB\\\"C"                         "AB\"C"
  "AB\\\'C"                         "AB\'C"
  L"\'AB\\\"C\'"                    L'AB\"C'
  "\'AB\\\'C\'"                     'AB\'C'
  H"{0, L\"AB\\\"B\", \'ab\\\"c\'}" {0, L"AB\"B", 'ab\"c'}

Cc: Liming Gao <liming.gao@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Yunhua Feng <yunhuax.feng@intel.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>