Broken --sysroot path generation for aarch64 cross-builds

### Description

Looking closely at the generated compiler command invocation for an aarch64 build, the `--sysroot` flag is pointing to a single `.so` file instead of the SDK root directory:

`--sysroot=external/score_bazel_cpp_toolchains++gcc+score_cc_autosd10_aarch64_pkg/lib64/CP1252.so`

The template logic generating the sysroot path variable appears to grab the wrong file path from the resolved target package.

This is the output that is generated

> external/score_bazel_cpp_toolchains++gcc+score_cc_autosd10_aarch64_pkg/usr/bin/g++ -U_FORTIFY_SOURCE '-D_XOPEN_SOURCE=700' -fstack-protector '-fdiagnostics-color=always' -fno-omit-frame-pointer -ffunction-sections -fdata-sections -fno-canonical-system-headers -no-canonical-prefixes '-z noexecstack' '-std=c++17' -MD -MF bazel-out/k8-fastbuild/bin/external/score_baselibs+/score/result/_objs/error/error_domain.pic.d '-frandom-seed=bazel-out/k8-fastbuild/bin/external/score_baselibs+/score/result/_objs/error/error_domain.pic.o' -fPIC -iquote external/score_baselibs+ -iquote bazel-out/k8-fastbuild/bin/external/score_baselibs+ '-D__DATE__="redacted"' '-D__TIMESTAMP__="redacted"' '-D__TIME__="redacted"' -Wno-builtin-macro-redefined -Wall -Wcast-align -Wcast-qual -Wformat-nonliteral -Wformat-signedness '-Wformat=2' -Wmissing-format-attribute -Wpointer-arith -Wredundant-decls -Wreturn-local-addr -Wsizeof-array-argument -Wundef -Wwrite-strings -Wodr -Wreorder -Wbool-compare -Wconversion -Wdouble-promotion -Wextra -Winvalid-pch -Wlogical-not-parentheses -Wlogical-op -Wpedantic -Wswitch-bool -Wunused-but-set-parameter -Wvla -Wnarrowing -nostdinc++ -isystem external/score_bazel_cpp_toolchains++gcc+score_cc_autosd10_aarch64_pkg/usr/include/c++/14 -isystem external/score_bazel_cpp_toolchains++gcc+score_cc_autosd10_aarch64_pkg/usr/include/c++/14/aarch64-redhat-linux -isystem external/score_bazel_cpp_toolchains++gcc+score_cc_autosd10_aarch64_pkg/usr/include/c++/14/backward -nostdinc -isystem external/score_bazel_cpp_toolchains++gcc+score_cc_autosd10_aarch64_pkg/usr/lib/gcc/aarch64-redhat-linux/14/include -isystem external/score_bazel_cpp_toolchains++gcc+score_cc_autosd10_aarch64_pkg/usr/include '--**sysroot=external/score_bazel_cpp_toolchains++gcc+score_cc_autosd10_aarch64_pkg/lib64/CP1252.so**' -c external/score_baselibs+/score/result/error_domain.cpp -o bazel-out/k8-fastbuild/bin/external/score_baselibs+/score/result/_objs/error/error_domain.pic.o)
> aarch64-binfmt-P: Could not open '/lib/ld-linux-aarch64.so.1': No such file or directory

### Analysis results

_No response_

### Solution

_No response_

### Error Occurrence Rate

Reproducible

### How to reproduce

- Use score_bazel_cpp_toolchains version 1.0.3.
- use autosd toolchain:

> gcc = use_extension("@score_bazel_cpp_toolchains//extensions:gcc.bzl", "gcc")
> gcc.toolchain(
> name = "score_cc_autosd10_aarch64",
> runtime_ecosystem = "autosd10",
> sdp_to_link = "score_cc_autosd10_aarch64_pkg",
> target_cpu = "aarch64",
> target_os = "linux",
> use_default_package = True,
> )

Build any cc target

### Supporting Information

_No response_

### Classification

Major

### First Affected Release

0.5

### Last Affected Release

1.0

### Expected Fixed Release

before release (main)

### Category

- [ ] Safety Relevant
- [ ] Security Relevant