Improve x/profiles params structure

[RiccardoM]

Context

Currently the x/profiles parameters are represented by the following structures:

type Params struct {
  NicknameParams NicknameParams
  DTagParams     DTagParams
  MaxBioLength   sdk.Int
}

type NicknameParams struct {
  MinNicknameLength sdk.Int
  MaxNicknameLength sdk.Int
}

type DTagParams struct {
  RegEx         string
  MinDTagLength sdk.Int
  MaxDTagLength sdk.Int
}

In my opinion there are a bunch of things that can be improved about these structures:

1. There are many redundant suffixes (Params, Nickname, etc)
2. The bio params are not inside a subset of their own

Implementation proposal

To improve the structure of the parameters I think we can re-defined them as follows:

type Params struct {
  Nickanme Nickname
  DTag     DTag
  Bio   Bio
}

type Nickname struct {
  MinLength sdk.Int
  MaxLength sdk.Int
}

type DTag struct {
  ValidityRegEx         string
  MinLength sdk.Int
  MaxLength sdk.Int
}

type Bio struct {
  MaxLenght sdk.Int
}

[leobragaz]

Even though I think these changes are necessaries, while implementing this I felt that these names are too generic and may be a bit confusing in the long run, especially when others will put their hands on the code.
I have think about changing them like this:

type Params struct {
  NicknameLimits NicknameLimits
  DTagPolicies DTagPolicies
  BioLimits BioLimits
}

type NicknameLimits struct {
  MinLength sdk.Int
  MaxLength sdk.Int
}

type DTagPolicies struct {
  ValidityRegEx string
  MinLength sdk.Int
  MaxLength sdk.Int
}

type BioLimits struct {
  MaxLength sdk.Int
}

let me know what you think @RiccardoM

[RiccardoM]

@bragaz I agree these names are more detailed. Can we just use Nickname, DTag and Bio for the field names though? Since they are fields of the Params struct I think we can remove the Limits and Policies suffixes. Also I think we can then revert to the old struct naming. What bothered me were only the field names:

type Params struct {
  Nickname NicknameParams
  DTag DTagParams
  Bio BioParams
}