Tracing requires liboffload to be initialized, so calling
isTracingEnabled() before olInit always returns false. This caused the
first trace log to look like:
```
-> OL_SUCCESS
```
instead of:
```
---> olInit() -> OL_SUCCESS
```
This patch moves the pre-call trace print for olInit so it is emitted
only after initialization.

It would be possible to add extra logic to detect whether liboffload is
already initialized and only postpone the first pre-call print, but this
would add unnecessary complexity, especially since this is tablegen
code. The difference would matter only in the unlikely case of a crash
during a second olInit call.

---------

Co-authored-by: Joseph Huber <huberjn@outlook.com>

Introduced in OpenMP 6.0, the device UID shall be a unique identifier of
a device on a given system. (Not necessarily a UUID.) Since it is not
guaranteed that the (U)UIDs defined by the device vendor libraries, such
as HSA, do not overlap with those of other vendors, the device UIDs in
offload are always combined with the offload plugin name. In case the
vendor library does not specify any device UID for a given device, we
fall back to the offload-internal device ID.
The device UID can be retrieved using the `llvm-offload-device-info`
tool.

Summary:
This was not using the size previously queried and would fail when the
implementation actually verified it.

This is a tool similar to urinfo that simply prints properties of all
devices. The old openMP version has been ported to liboffload.

The order entries in the tablegen API files are iterated is not the
order
they appear in the file. To avoid any issues with the order changing
in future, we now generate all definitions of a certain class before
class that can use them.

This is a NFC; the definitions don't actually change, just the order
they exist in in the OffloadAPI.h header.

Add the following properties in Offload device info:
* VENDOR_ID
* NUM_COMPUTE_UNITS
* [SINGLE|DOUBLE|HALF]_FP_CONFIG
* NATIVE_VECTOR_WIDTH_[CHAR|SHORT|INT|LONG|FLOAT|DOUBLE|HALF]
* MAX_CLOCK_FREQUENCY
* MEMORY_CLOCK_RATE
* ADDRESS_BITS
* MAX_MEM_ALLOC_SIZE
* GLOBAL_MEM_SIZE

Add a bitfield option to enumerators, allowing the values to be
bit-shifted instead of incremented. Generate the per-type enums using
`foreach` to reduce code duplication.

Use macros in unit test definitions to reduce code duplication.

libc++ headers must be generated before compiling part of liboffload. 
The build error occurs if clang is configured to use libc++ by default. 
Fixes issue #149324