expose custom PVM settings in the standard json interface (#318)

Exposes the following PolkaVM specific options via the standard json
interface:
- Heap size
- Stack size
- Whether to emit source level debug information

Additionally it is now forbidden to specify those as CLI option in
standard JSON mode. They are bytecode altering options and having
multiple ways to specify them creates unnecessary room for confusion:
The standard JSON input description should be sufficient and succint for
reproducible builds.

Closes #290

---------

Signed-off-by: xermicus <bigcyrill@hotmail.com>

crates/llvm-context/src/lib.rs

@@ -5,7 +5,6 @@ use std::sync::OnceLock;
 
 pub use self::debug_config::ir_type::IRType as DebugConfigIR;
 pub use self::debug_config::DebugConfig;
-pub use self::memory::MemoryConfig;
 pub use self::optimizer::settings::size_level::SizeLevel as OptimizerSettingsSizeLevel;
 pub use self::optimizer::settings::Settings as OptimizerSettings;
 pub use self::optimizer::Optimizer;
@@ -76,7 +75,6 @@ pub use self::target_machine::target::Target;
 pub use self::target_machine::TargetMachine;
 
 pub(crate) mod debug_config;
-pub(crate) mod memory;
 pub(crate) mod optimizer;
 pub(crate) mod polkavm;
 pub(crate) mod target_machine;