internal: switch from CLI to internal benchmarking

We have a CLI for benchmarking, but no one actually uses it it seems.
Let's try switching to "internal" benchmarks, implemented as rust tests.
They should be easier to "script" to automate tracking of perf
regressions.

crates/rust-analyzer/src/cli.rs

@@ -1,8 +1,7 @@
 //! Various batch processing tasks, intended primarily for debugging.
 
-mod load_cargo;
+pub(crate) mod load_cargo;
 mod analysis_stats;
-mod analysis_bench;
 mod diagnostics;
 mod progress_report;
 mod ssr;
@@ -15,7 +14,6 @@ use syntax::{AstNode, SourceFile};
 use vfs::Vfs;
 
 pub use self::{
-    analysis_bench::{BenchCmd, BenchWhat, Position},
     analysis_stats::AnalysisStatsCmd,
     diagnostics::diagnostics,
     load_cargo::{load_workspace, load_workspace_at, LoadCargoConfig},