Serialize DSLX Type Information

In the bazel rule, dslx_library, serialize type information from parse and type check task for use by other rules to avoid recomputing type information.

For example:
```
# Serialize type information from parse and type check task so it can be used by target c.
dslx_library(
name = "a",
srcs = [
"a.x",
],
)

# Depends on target a.
# Use serialized type information from target a to avoid recomputing the parsing and type checking task of a.
dslx_library(
name = "c",
srcs = [
"c.x",
],
deps = [
":a",
],
)
```
Reference: https://github.com/google/xls/issues/311