aconfig Rust: Support huge list of flags

Test: m libbluetooth_aconfig_flags_rust
Test: atest aconfig.prod_mode.test.rust
Test: atest aconfig.test_mode.test.rust
Test: atest aconfig.force_read_only_mode.test.rust
Test: atest aconfig.test
Bug: 311772251
Bug: 362773105
Change-Id: I48e268fc783e491a045d1bb6298c2b3c87045722