improvement: better literal support

[baszalmstra]

This PR will add support for:

• typed literals (100u8) (Add int and float literal type suffixes #121)
• hex literals, binary literals, octal literals (Add hexadecimal, octal, and binary int literals #119)
• underscores in numeric literals (Add int and float literals with underscore spacing #120)

Progress

• Generating typed literals in LLVM
• Proper parsing of hex integers
• Proper parsing of binary integers
• Proper parsing of octal integers
• Stripping of underscores while parsing
• Parsing of suffixes in literals
• Using suffix name for typing information
• Error handling for invalid suffix names
• Error handling for invalid literals (0b10102)
• Error handling for literals that exceed the size of their suffix

Out of scope

This PR does not implement literal type inferencing (#118).

[codecov]

Codecov Report

Merging #122 into master will increase coverage by 0.80%.
The diff coverage is 83.92%.

@@            Coverage Diff             @@
##           master     #122      +/-   ##
==========================================
+ Coverage   81.92%   82.72%   +0.80%     
==========================================
  Files         141      147       +6     
  Lines        9055     9704     +649     
==========================================
+ Hits         7418     8028     +610     
- Misses       1637     1676      +39     

Impacted Files	Coverage Δ
crates/mun_codegen/src/db.rs	100.00% <ø> (ø)
crates/mun_compiler/src/driver.rs	78.84% <ø> (ø)
crates/mun_hir/src/ty.rs	91.02% <ø> (ø)
crates/mun_syntax/src/tests/lexer.rs	100.00% <ø> (ø)
crates/mun_target/src/lib.rs	100.00% <ø> (ø)
crates/mun_target/src/spec.rs	80.00% <ø> (ø)
crates/mun_hir/src/ty/infer.rs	79.29% <47.82%> (-1.27%)	⬇️
crates/mun_target/src/abi/mod.rs	56.73% <56.73%> (ø)
...mun_hir/src/expr/validator/literal_out_of_range.rs	58.33% <58.33%> (ø)
crates/mun_hir/src/diagnostics.rs	70.50% <64.70%> (-1.19%)	⬇️
... and 36 more

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[Wodann]

Once again, a very clean PR. Looking good!

[baszalmstra]

The coverage diff on the last commits is pretty low because I included code from rustc_targets which does not contain tests. I'm also not using everything from the code but I added it nonetheless because I feel like it might benefit us in the future.