Remove submodules, use CMake's FetchContent instead. #110

Job	Run time
Checkout EASTL	20s
Build EASTL (windows-latest, msvc, Debug, std_iter_category_disabled)	2m 51s
Build EASTL (windows-latest, msvc, Debug, std_iter_category_enabled)	2m 50s
Build EASTL (windows-latest, msvc, Release, std_iter_category_disabled)	5m 19s
Build EASTL (windows-latest, msvc, Release, std_iter_category_enabled)	4m 45s
Build EASTL (ubuntu-latest, clang, Debug, std_iter_category_disabled)	2m 35s
Build EASTL (ubuntu-latest, clang, Debug, std_iter_category_enabled)	2m 43s
Build EASTL (ubuntu-latest, clang, Release, std_iter_category_disabled)	2m 23s
Build EASTL (ubuntu-latest, clang, Release, std_iter_category_enabled)	3m 26s
Build EASTL (ubuntu-latest, gcc, Debug, std_iter_category_disabled)	3m 35s
Build EASTL (ubuntu-latest, gcc, Debug, std_iter_category_enabled)	3m 51s
Build EASTL (ubuntu-latest, gcc, Release, std_iter_category_disabled)	2m 50s
Build EASTL (ubuntu-latest, gcc, Release, std_iter_category_enabled)	2m 46s
Run EASTL tests (windows-latest, msvc, Debug)	57s
Run EASTL benchmarks (windows-latest, msvc, Release)	24s
Run EASTL tests (windows-latest, msvc, Release)	1m 8s
Run EASTL benchmarks (ubuntu-latest, clang, Release)	44s
Run EASTL tests (ubuntu-latest, clang, Debug)	1m 8s
Run EASTL benchmarks (ubuntu-latest, gcc, Release)	1m 15s
Run EASTL tests (ubuntu-latest, clang, Release)	35s
Run EASTL tests (ubuntu-latest, gcc, Debug)	25s
Run EASTL tests (ubuntu-latest, gcc, Release)	20s
	47m 10s

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