Deprecate `install_*`

[hadley]

And point folks to pak::pak() instead

[hadley]

And update_packages() and dev_package_deps().

[hadley]

And github_pull + github_release

[jennybc]

Relates to #2486

[hadley]

The basic idea is to get out of the business of re-exporting remotes functions, instead recommending modern pak equivalents where possible, otherwise directing to an explicit remotes call. All of the following would be deprecated:

• install_bioc() -> pak::pak()
• install_bitbucket() -> remotes::install_bitbucket()
• install_cran() -> pak::pak()
• install_dev() -> remotes::install_dev()
• install_git() -> pak::pak("git:...)
• install_github() -> pak::pak()
• install_gitlab() -> pak::pak("gitlab:...")
• install_local() -> pak::pak("local:...")
• install_svn() -> remotes::install_svn()
• install_url() -> pak::pak("url:...")
• install_version() -> pak::pak()
• update_packages() -> pak::pak()
• dev_package_deps() -> pak::local_dev_deps()
• github_pull() -> remotes::github_pull()
• github_release() -> remotes::github_release()