Separate compilation and linker phases (#376)

Separate between compilation and linker phases to allow deploy time
linking and back-porting era compiler changes to fix #91. Unlinked
contract binaries (caused by missing libraries or missing factory
dependencies in turn) are emitted as raw ELF object.

Few drive by fixes:
- #98
- A compiler panic on missing libraries definitions.
- Fixes some incosistent type forwarding in JSON output (empty string
vs. null object).
- Remove the unused fallback for size optimization setting.
- Remove the broken `--lvm-ir`  mode.
- CI workflow fixes.

---------

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>
Signed-off-by: xermicus <bigcyrill@hotmail.com>
Signed-off-by: xermicus <cyrill@parity.io>

crates/llvm-context/src/polkavm/const/mod.rs

@@ -1,10 +1,12 @@
 //! The LLVM context constants.
 
+use revive_common::{BIT_LENGTH_X32, BYTE_LENGTH_WORD};
+
 /// The LLVM framework version.
 pub const LLVM_VERSION: semver::Version = semver::Version::new(18, 1, 4);
 
 /// The pointer width sized type.
-pub static XLEN: usize = revive_common::BIT_LENGTH_X32;
+pub static XLEN: usize = BIT_LENGTH_X32;
 
 /// The calldata size global variable name.
 pub static GLOBAL_CALLDATA_SIZE: &str = "calldatasize";
@@ -20,4 +22,4 @@ pub static GLOBAL_ADDRESS_SPILL_BUFFER: &str = "address_spill_buffer";
 
 /// The deployer call header size that consists of:
 /// - bytecode hash (32 bytes)
-pub const DEPLOYER_CALL_HEADER_SIZE: usize = revive_common::BYTE_LENGTH_WORD;
+pub const DEPLOYER_CALL_HEADER_SIZE: usize = BYTE_LENGTH_WORD;