add separated runs by UUID (backport #9367) (#9380)

* add separated runs by UUID (#9367)

This _should_ be the last piece needed for this tool.
This allows the tool to generate reports on multiple experimental runs that may have been performed against the same chain.

The `load` tool has been updated to generate a `UUID` on startup to uniquely identify each experimental run. The `report` tool separates all of the results it reads by `UUID` and performs separate calculations for each discovered experiment.

Sample output is as follows

```
Experiment ID: 6bd7d1e8-d82c-4dbe-a1b3-40ab99e4fa30

        Connections: 1
        Rate: 1000
        Size: 1024

        Total Valid Tx: 9000
        Total Negative Latencies: 0
        Minimum Latency: 86.632837ms
        Maximum Latency: 1.151089602s
        Average Latency: 813.759361ms
        Standard Deviation: 225.189977ms

Experiment ID: 453960af-6295-4282-aed6-367fc17c0de0

        Connections: 1
        Rate: 1000
        Size: 1024

        Total Valid Tx: 9000
        Total Negative Latencies: 0
        Minimum Latency: 79.312992ms
        Maximum Latency: 1.162446243s
        Average Latency: 422.755139ms
        Standard Deviation: 241.832475ms

Total Invalid Tx: 0
```

closes: #9352

#### PR checklist

- [ ] Tests written/updated, or no tests needed
- [ ] `CHANGELOG_PENDING.md` updated, or no changelog entry needed
- [ ] Updated relevant documentation (`docs/`) and code comments, or no
      documentation updates needed

(cherry picked from commit 1067ba1571)

# Conflicts:
#	go.mod

* fix merge conflict

* fix lint

Co-authored-by: William Banfield <4561443+williambanfield@users.noreply.github.com>
Co-authored-by: William Banfield <wbanfield@gmail.com>

test/loadtime/cmd/load/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 
+	"github.com/google/uuid"
 	"github.com/informalsystems/tm-load-test/pkg/loadtest"
 	"github.com/tendermint/tendermint/test/loadtime/payload"
 )
@@ -20,6 +21,7 @@ type ClientFactory struct{}
 // TxGenerator holds the set of information that will be used to generate
 // each transaction.
 type TxGenerator struct {
+	id    []byte
 	conns uint64
 	rate  uint64
 	size  uint64
@@ -49,7 +51,9 @@ func (f *ClientFactory) ValidateConfig(cfg loadtest.Config) error {
 }
 
 func (f *ClientFactory) NewClient(cfg loadtest.Config) (loadtest.Client, error) {
+	u := [16]byte(uuid.New())
 	return &TxGenerator{
+		id:    u[:],
 		conns: uint64(cfg.Connections),
 		rate:  uint64(cfg.Rate),
 		size:  uint64(cfg.Size),
@@ -61,5 +65,6 @@ func (c *TxGenerator) GenerateTx() ([]byte, error) {
 		Connections: c.conns,
 		Rate:        c.rate,
 		Size:        c.size,
+		Id:          c.id,
 	})
 }