Resolve "Allow users to specify pronouns"

What does this MR do?

This is a very basic MVC for #332405 🙂

This change:

• Allows a user to set their pronouns from the /-/profile page. (Its not a list, so users can write their own pronouns in the text field)

• Displays the set pronouns adjacent to their name in /:username page.

DB Migrations

UP migrations

rake db:migrate

== 20210603140302 AddPronounsToUserDetails: migrating =========================
-- add_column(:user_details, :pronouns, :text, {:null=>true})
   -> 0.0023s
== 20210603140302 AddPronounsToUserDetails: migrated (0.0098s) ================

== 20210607050531 AddTextLimitToUserDetailsPronouns: migrating ================
-- transaction_open?()
   -> 0.0000s
-- current_schema()
   -> 0.0004s
-- execute("ALTER TABLE user_details\nADD CONSTRAINT check_eeeaf8d4f0\nCHECK ( char_length(pronouns) <= 50 )\nNOT VALID;\n")
   -> 0.0045s
-- current_schema()
   -> 0.0003s
-- execute("SET statement_timeout TO 0")
   -> 0.0006s
-- execute("ALTER TABLE user_details VALIDATE CONSTRAINT check_eeeaf8d4f0;")
   -> 0.0018s
-- execute("RESET ALL")
   -> 0.0006s
== 20210607050531 AddTextLimitToUserDetailsPronouns: migrated (0.0173s) =======

DOWN migrations

rake db:migrate:down VERSION=20210607050531

== 20210607050531 AddTextLimitToUserDetailsPronouns: reverting ================
-- execute("ALTER TABLE user_details\nDROP CONSTRAINT IF EXISTS check_eeeaf8d4f0\n")
   -> 0.0038s
== 20210607050531 AddTextLimitToUserDetailsPronouns: reverted (0.0152s) =======

rake db:migrate:down VERSION=20210603140302

== 20210603140302 AddPronounsToUserDetails: reverting =========================
-- remove_column(:user_details, :pronouns)
   -> 0.0031s
== 20210603140302 AddPronounsToUserDetails: reverted (0.0131s) ================

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• I have included a changelog entry, or it's not needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• [-] I have tested this MR in all supported browsers, or it's not needed.
• [-] I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.

Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team