MRG: validate param strings (#114)

Thus far, we haven't checked for invalid or repeated parameters within a
param string, or other issues that may arise. This PR checks each param
string, errors appropriately with any issues, and adds rust-level tests
for param string parsing. Having these checks in the `BuildParams` and
`BuildParamsSet` make them simple to use across different sketching
utilities.

Since I wrote a bunch of rust-level tests, I added rust testing to the
github actions workflow.

I also make sure we're using the param.moltype rather than the input
moltype to build each record, and reverted to using a simple bool for
abundance tracking.

- fixes #116

.github/workflows/build-test.yml

@@ -53,10 +53,14 @@ jobs:
     - name: Run cargo fmt
       run: cargo fmt --all -- --check --verbose
 
+    - name: rust tests
+      run: cargo test --verbose --no-fail-fast
+
     - name: build
       shell: bash -l {0}
       run: make
 
-    - name: test
+    - name: python tests
       shell: bash -l {0}
       run: pytest
+