tp: remove experimental package and diffuse contents into other packages

This CL removes the central "experimental" module from the stdlib. This
module's design was a bit of a mistake as it became a central dumping
ground for randoming things without clear ownership. Also making the
tables visible in the documentation while not being something people
should depend on was a bit of a misnomer.

Instead diffuse the modules inside into other packages and make all the
experimental_ prefixed tables just _ (i.e. internal tables which ~have
the same guarantees of being breakable at any time).

Change-Id: I7f2b85476f6bb53690ec2900d542463f184900d6

ui/src/frontend/app.ts

diff --git a/ui/src/frontend/app.ts b/ui/src/frontend/app.ts
index ae4c38b..015b893 100644
--- a/ui/src/frontend/app.ts
+++ b/ui/src/frontend/app.ts
@@ -323,7 +323,7 @@
 
             if (engine !== undefined && trackUtid != 0) {
               await runQuery(
-                `SELECT IMPORT('experimental.thread_executing_span');`,
+                `SELECT IMPORT('sched.thread_executing_span');`,
                 engine);
               await addDebugSliceTrack(
                 engine,
@@ -338,7 +338,7 @@
                       process.name AS process_name,
                       'thread_state' AS table_name
                     FROM
-                      experimental_thread_executing_span_critical_path(
+                      _thread_executing_span_critical_path(
                           ${trackUtid},
                           ${window.start},
                           ${window.end} - ${window.start}) cr
@@ -365,7 +365,7 @@
 
             if (engine !== undefined && trackUtid != 0) {
               await runQuery(
-                `SELECT IMPORT('experimental.thread_executing_span');`,
+                `SELECT IMPORT('sched.thread_executing_span');`,
                 engine);
               await addDebugSliceTrack(
                 engine,
@@ -399,10 +399,10 @@
 
             if (engine !== undefined && trackUtid != 0) {
               addQueryResultsTab({
-                query: `SELECT IMPORT('experimental.thread_executing_span');
+                query: `SELECT IMPORT('sched.thread_executing_span');
                    SELECT *
                       FROM
-                        experimental_thread_executing_span_critical_path_graph(
+                        _thread_executing_span_critical_path_graph(
                         "criical_path",
                          ${trackUtid},
                          ${window.start},

ui/src/frontend/thread_state_tab.ts

diff --git a/ui/src/frontend/thread_state_tab.ts b/ui/src/frontend/thread_state_tab.ts
index 3d4047f..1c881ec 100644
--- a/ui/src/frontend/thread_state_tab.ts
+++ b/ui/src/frontend/thread_state_tab.ts
@@ -291,7 +291,7 @@
     ), m(Button,
       {
         label: 'Critical path lite',
-        onclick: () => runQuery(`INCLUDE PERFETTO MODULE experimental.thread_executing_span;`, this.engine)
+        onclick: () => runQuery(`INCLUDE PERFETTO MODULE sched.thread_executing_span;`, this.engine)
           .then(() => addDebugSliceTrack(
             this.engine,
             {
@@ -306,7 +306,7 @@
                       process.name AS process_name,
                       'thread_state' AS table_name
                     FROM
-                      experimental_thread_executing_span_critical_path(
+                      _thread_executing_span_critical_path(
                         ${this.state?.thread?.utid},
                         trace_bounds.start_ts,
                         trace_bounds.end_ts - trace_bounds.start_ts) cr,
@@ -323,7 +323,7 @@
     ), m(Button,
       {
         label: 'Critical path',
-        onclick: () => runQuery(`INCLUDE PERFETTO MODULE experimental.thread_executing_span;`, this.engine)
+        onclick: () => runQuery(`INCLUDE PERFETTO MODULE sched.thread_executing_span;`, this.engine)
           .then(() => addDebugSliceTrack(
             this.engine,
             {
@@ -331,7 +331,7 @@
                   `
                     SELECT cr.id, cr.utid, cr.ts, cr.dur, cr.name, cr.table_name
                       FROM
-                        experimental_thread_executing_span_critical_path_stack(
+                        _thread_executing_span_critical_path_stack(
                           ${this.state?.thread?.utid},
                           trace_bounds.start_ts,
                           trace_bounds.end_ts - trace_bounds.start_ts) cr,