Introduce getters for components of a QuasiNewtonModel #317

Job	Run time
Julia lts - macos-latest - x64 - pull_request	3m 13s
Julia 1 - macos-15-intel - x64 - pull_request	4m 22s
Julia lts - macos-15-intel - x64 - pull_request	2m 43s
Julia 1 - macos-latest - x64 - pull_request	5m 7s
Julia lts - ubuntu-latest - x64 - pull_request	1m 53s
Julia pre - windows-latest - x64 - pull_request	3m 0s
Julia lts - windows-latest - x64 - pull_request	2m 46s
Julia 1 - macos-latest - arm64 - pull_request	2m 36s
Julia pre - ubuntu-latest - x64 - pull_request	1m 51s
Julia 1 - ubuntu-24.04-arm - arm64 - pull_request	2m 47s
Julia 1 - windows-latest - x64 - pull_request	4m 4s
Julia pre - macos-latest - x64 - pull_request	3m 10s
Julia 1 - ubuntu-latest - x64 - pull_request	3m 29s
	41m 1s

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