[adapters] only export get proc table symbols in adapters

[pbalcer]

This adds a version script to restrict visiblity of symbols in adapters. This is so that adapters don't use loader ur functions when populating proc tables...

Before:

piotrekpc :: unified-runtime/build/bin ‹adapters-ci*› » UR_ADAPTERS_FORCE_LOAD=../lib/libur_adapter_hip.so ./hello_world
AddressSanitizer:DEADLYSIGNAL
=================================================================
==84218==ERROR: AddressSanitizer: stack-overflow on address 0x7ffe394fefc0 (pc 0x7f843eac49b1 bp 0x7ffe394ff0d0 sp 0x7ffe394fefc0 T0)
    #0 0x7f843eac49b1 in void std::call_once<urInit::$_0>(std::once_flag&, urInit::$_0&&) /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.1.1/../../../../include/c++/13.1.1/mutex:897
    #1 0x7f843eac44d2 in urInit /home/piotrek/work/unified-runtime/source/loader/ur_libapi.cpp:48:5
    #2 0x7f843eac472e in urInit /home/piotrek/work/unified-runtime/source/loader/ur_libapi.cpp:61:12
    ...
    #245 0x7f843eac472e in urInit /home/piotrek/work/unified-runtime/source/loader/ur_libapi.cpp:61:12
    #246 0x7f843eac472e in urInit /home/piotrek/work/unified-runtime/source/loader/ur_libapi.cpp:61:12

SUMMARY: AddressSanitizer: stack-overflow /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/13.1.1/../../../../include/c++/13.1.1/mutex:897 in void std::call_once<urInit::$_0>(std::once_flag&, urInit::$_0&&)
==84218==ABORTING

piotrekpc :: unified-runtime/build/lib ‹adapters-ci*› » nm libur_adapter_hip.so
...
000000000011b5c0 T urGetUsmP2PExpProcAddrTable
0000000000119ee0 T urGetUSMProcAddrTable
00000000001a6c40 T urInit
0000000000185bc0 T urKernelCreate
000000000018a540 T urKernelCreateWithNativeHandle
...

After:

piotrekpc :: unified-runtime/build/bin ‹adapters-ci*› » UR_ADAPTERS_FORCE_LOAD=../lib/libur_adapter_hip.so ./hello_world
Platform initialized.
API version: 0.6
Found a AMD Radeon RX 7900 XT gpu.

=================================================================
==85366==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 144 byte(s) in 2 object(s) allocated from:
    #0 0x5625a26c0202 in operator new(unsigned long) (/home/piotrek/work/unified-runtime/build/bin/hello_world+0x126202) (BuildId: bf43e9d3666a60ce9d2a785e91b9c26426eabfd0)
    #1 0x7f5095457651  (/opt/rocm/lib/libhsa-runtime64.so.1+0x57651) (BuildId: f7f526d06338fb02490caa9445ee3ad876fcab4f)

    ...

Indirect leak of 24 byte(s) in 1 object(s) allocated from:
    #0 0x5625a26c0202 in operator new(unsigned long) (/home/piotrek/work/unified-runtime/build/bin/hello_world+0x126202) (BuildId: bf43e9d3666a60ce9d2a785e91b9c26426eabfd0)
    #1 0x7f5095aa0722  (/opt/rocm/hip/lib/libamdhip64.so.5+0x2a0722) (BuildId: fb16c579f66b7bf10313de1f62a8fd7f64a0f860)

Indirect leak of 16 byte(s) in 1 object(s) allocated from:
    #0 0x5625a26c0202 in operator new(unsigned long) (/home/piotrek/work/unified-runtime/build/bin/hello_world+0x126202) (BuildId: bf43e9d3666a60ce9d2a785e91b9c26426eabfd0)
    #1 0x7f4f89da9dab  (/opt/rocm/lib/libamd_comgr.so.2+0x9a9dab) (BuildId: 80900645c6c6d589df59db110a00d470d77ab376)

SUMMARY: AddressSanitizer: 3495 byte(s) leaked in 55 allocation(s).

piotrekpc :: unified-runtime/build/lib ‹adapters-ci*› » nm libur_adapter_hip.so
...
00000000000a76b0 T urGetUsmP2PExpProcAddrTable
00000000000a5fd0 T urGetUSMProcAddrTable
0000000000132d30 t urInit
0000000000111cb0 t urKernelCreate
0000000000116630 t urKernelCreateWithNativeHandle
...