command line flags: dashes and underscores synonyms

[shlomi-noach]

As pointed by @deepthi here we have a mixture of dash and underscore in our command line flags. Examples:

vitess/go/cmd/vttablet/vttablet.go

Lines 51 to 52 in 4fea10e

	tabletPath = flag.String("tablet-path", "", "tablet alias")
	tabletConfig = flag.String("tablet_config", "", "YAML file config for tablet")

vitess/go/vt/vttablet/tabletserver/tabletenv/config.go

Lines 148 to 151 in 4fea10e

	flag.BoolVar(&currentConfig.EnforceStrictTransTables, "enforce_strict_trans_tables", defaultConfig.EnforceStrictTransTables, "If true, vttablet requires MySQL to run with STRICT_TRANS_TABLES or STRICT_ALL_TABLES on. It is recommended to not turn this flag off. Otherwise MySQL may alter your supplied values before saving them to the database.")
	flag.BoolVar(&enableConsolidator, "enable-consolidator", true, "This option enables the query consolidator.")
	flag.BoolVar(&enableConsolidatorReplicas, "enable-consolidator-replicas", false, "This option enables the query consolidator only on replicas.")
	flag.BoolVar(&currentConfig.CacheResultFields, "enable-query-plan-field-caching", defaultConfig.CacheResultFields, "This option fetches & caches fields (columns) when storing query plans")

and so on...

This is confusing. We should align on a standard. But we also obviously want to maintain backwards compatibility. I found this on a related discussion and am suggesting we can go down that path: we'll standardize on underscored, and make dash-based flags synonyms. Thus, -enable-lag-throtler and -enable_lag_throttler will be synonyms.

Sample PR to follow to illustrate.

[shlomi-noach]

#7406 as an example

[shlomi-noach]

on vttablet-side, this is fixed by #7406

I'll proceed to check other apps, namely vtctld