[mlir][SPIR-V] Add Weak linkage type and SPV_AMD_weak_linkage extension (#195660)
- add 'Weak' linkage type (SPV_AMD_weak_linkage)
- deduce the Linkage capability and linkage-type extension from
linkage_attributes in UpdateVCE pass
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Co-authored-by: Jakub Kuderski <kubakuderski@gmail.com>