et2lst implemented

[jodavaho]

Following what appears to be the standard way of doing it, I implemented et2lst. This is kind of a test case to make sure I hit everything.

Note, I detected and fixed some warnings in the pre-hook tests, but could not get past unit testing due to some hard-coded paths.

check for added large files..........................................................Passed
check that executables have shebangs.............................(no files to check)Skipped
check for merge conflicts............................................................Passed
check toml.......................................................(no files to check)Skipped
check yaml.......................................................(no files to check)Skipped
fix end of files.....................................................................Passed
trim trailing whitespace.............................................................Passed
markdownlint.....................................................(no files to check)Skipped
Format YAML files................................................(no files to check)Skipped
fmt..................................................................................Passed
cargo check..........................................................................Passed
clippy...............................................................................Passed
Compile and execute unit and integration tests for all targets.......................Failed
- hook id: execute-tests
- exit code: 1

   Compiling rust-spice-derive v0.7.6 (/home/hook/FB/ws/rust-spice/rust-spice-derive)
   Compiling rust-spice v0.7.8 (/home/hook/FB/ws/rust-spice/rust-spice)
    Finished test [unoptimized + debuginfo] target(s) in 0.72s
     Running unittests src/lib.rs (target/debug/deps/spice-c93f4cd88b5e353f)

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

     Running tests/lib.rs (target/debug/deps/lib-a6ca4379499362e1)

running 20 tests
 
================================================================================
 
Toolkit version: N0067
 
SPICE(NOSUCHFILE) --
 
The attempt to load
"/Users/gregoireh/data/spice-kernels/hera/kernels/mk/hera_study_PO_EMA_2024.tm"
by the routine FURNSH failed. It could not be located.
 
A traceback follows.  The name of the highest level module is first.
furnsh_c --> FURNSH --> ZZLDKER
 
Oh, by the way:  The SPICELIB error handling actions are USER-TAILORABLE.  You
can choose whether the Toolkit aborts or continues when errors occur, which
error messages to output, and where to send the output.  Please read the ERROR
"Required Reading" file, or see the routines ERRACT, ERRDEV, and ERRPRT.
 
================================================================================
error: test failed, to rerun pass `-p rust-spice --test lib`

Caused by:
  process didn't exit successfully: `/home/hook/FB/ws/rust-spice/target/debug/deps/lib-a6ca4379499362e1` (exit status: 1)
note: test exited abnormally; to see the full output pass --nocapture to the harness.

[jodavaho]

Hi @GregoireHENRY this is mostly a test MR. I can implement more functions than this, but wanted a minimal one to make sure I'm following contribution guidelines as best I can.