Add `HStrLen` method to `rueidiscompat`

[rueian]

HStrLen was merged into go-redis recently. We should add it to rueidiscompat as well:

rueidis/rueidiscompat/adapter.go

Lines 178 to 182 in c6c60a3

	HGetDel(ctx context.Context, key string, fields ...string) *StringSliceCmd
	HGetEX(ctx context.Context, key string, fields ...string) *StringSliceCmd
	HGetEXWithArgs(ctx context.Context, key string, options *HGetEXOptions, fields ...string) *StringSliceCmd
	HSetEX(ctx context.Context, key string, fieldsAndValues ...string) *IntCmd
	HSetEXWithArgs(ctx context.Context, key string, options *HSetEXOptions, fieldsAndValues ...string) *IntCmd

Please take a look at #831 for an example of how we added similar functions.

[rmarra]

Hello, can I work on this issue?

[rueian]

Hi @rmarra, thanks for the interest! While this issue has been solved by other PRs, you could take a look at other issues if you want to contribute.