orion cmake configuration fails when CMAKE_C_COMPILED_ID is not set […

…OI-1869] (#176)

## Jira Ticket

https://swift-nav.atlassian.net/browse/OI-1869

## Bug description

orion build fails with

```bash
CMake Error at third_party/orion-engine/third_party/auk/cmake/swift_nav/LanguageStandards.cmake:63 (if):
  if given arguments:

    "STREQUAL" "IAR"

  Unknown arguments specified
Call Stack (most recent call first):
  third_party/orion-engine/third_party/auk/cmake/swift_nav/SwiftTargets.cmake:351 (swift_set_language_standards)
  third_party/orion-engine/third_party/auk/cmake/swift_nav/SwiftTargets.cmake:373 (swift_add_target)
  proto/CMakeLists.txt:29 (swift_add_library)
```

CMake syntax allows using the variable without ${} to simultaneously
check if variable is defined, and variable content.


## Testing

Updated
`third_party/orion-engine/third_party/auk/cmake/swift_nav/LanguageStandards.cmake`
locally with the fix, CMake config runs correctly.

LanguageStandards.cmake

@@ -60,7 +60,7 @@ function(swift_set_language_standards)
  set(C_EXTENSIONS OFF)
  endif()
 
- if(${CMAKE_C_COMPILER_ID} STREQUAL "IAR")
+ if(CMAKE_C_COMPILER_ID STREQUAL "IAR")
  set_target_properties(${x_UNPARSED_ARGUMENTS}
  PROPERTIES
  C_STANDARD_REQUIRED ON