Update on "Add LoRA linear definition"

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Add lora linear definition. Pull out linears from attention, and allow custom linear (eg. lora linear) to be passed in.

If none, construct linear (current behaviour).

Differential Revision: [D73953776](https://our.internmc.facebook.com/intern/diff/D73953776/)

[ghstack-poisoned]

Author: lucylq

examples/models/llama/attention.py

@@ -6,6 +6,7 @@
 import torch.nn as nn
 import torch.nn.functional as F
 from executorch.examples.models.llama.model_args import ModelArgs
+from executorch.examples.models.llama.lora import LoRALinear
 from executorch.examples.models.llama.norm import RMSNorm
 from executorch.examples.models.llama.rope import Rope
 

examples/models/llama/llama_transformer.py

@@ -18,7 +18,6 @@
     ForwardOptions,
 )
 
-from executorch.examples.models.llama.lora import LoRALinear
 from executorch.examples.models.llama.model_args import ModelArgs
 from executorch.examples.models.llama.norm import RMSNorm
 from executorch.examples.models.llama.rope import Rope