[SYCL][UR] Log sycl-ls error messages related to adapter loading

[bratpiorka]

Changes:

• change the log level to "error" for all errors related to adapter dependencies during UR adapter loading
• enable the printing of UR adapter errors in sycl-ls from platform::get_platforms() using environment variables

With this PR, there will be no changes for the user in the default scenario where some adapters exist and some are missing (a missing adapter is not considered an error). In cases where a dependency is missing, the following example message will be displayed:

<LOADER>[ERROR]: failed to load adapter 'libur_adapter_level_zero.so.0' with error: libumf.so.0: cannot open shared object file: No such file or directory

Here is the message for missing symbols (a case where a dependency is not compatible with the rest of the libraries):

<LOADER>[ERROR]: failed to load adapter 'libur_adapter_level_zero.so.0' with error: /home/rrudnick/llvm/build/lib/libumf.so.0: version `UMF_0.10' not found (required by /home/rrudnick/llvm/build/lib/libur_adapter_level_zero.so.0)

[aelovikov-intel]

log sycl-ls error adapter loading messages

First, needs [SYCL][UR] tags prefix.
Second, should start with upper-case ("Log ...")
Third, doesn't seem to be a proper sentence, can you re-phrase please?

[bratpiorka]

First, needs [SYCL][UR] tags prefix.
Second, should start with upper-case ("Log ...")
Third, doesn't seem to be a proper sentence, can you re-phrase please?

thank you for noticing this, done

[aelovikov-intel]

First, needs [SYCL][UR] tags prefix.
Second, should start with upper-case ("Log ...")
Third, doesn't seem to be a proper sentence, can you re-phrase please?

thank you for noticing this, done

I think all of them apply still...

[bratpiorka]

@intel/llvm-gatekeepers please merge