Adding issue and merge request templates

.gitlab/issue_templates/bug.md

+<!--
+* Use this issue template for reporting a new bug.
+-->
+
+### Summary
+**Summarize the bug encountered concisely.**
+
+
+### Steps to reproduce:
+**How one can reproduce the issue - this is very important.**
+
+1. Step 1
+2. Step 2
+3. ...
+
+### What is the current bug behavior?
+**What actually happens.**
+
+
+### What is the expected behavior?
+**What you want to see instead**
+
+
+
+### Environment
+**Which operating system are you using? For example: Debian GNU/Linux 10.1, Windows 10, Ubuntu Xenial, FreeBSD 12.2, etc.**
+**Which installation method did you use? Distribution package (apt, pkg, homebrew), from source tarball, from Git, etc.**
+
+### Relevant logs and/or screenshots
+
+
+/label ~bug

.gitlab/merge_request_templates/default.md

+## Merge Info
+
+<!-- Bookkeeping information for release management -->
+
+### Related Issues
+- tor-browser#xxxxx
+- mullvad-browser#xxxxx
+- tor-browser-build#xxxxx
+
+### Backporting
+
+#### Timeline
+- [ ] **Immediate**: patchset needed as soon as possible
+- [ ] **Next Minor Stable Release**: patchset that needs to be verified in nightly before backport
+- [ ] **Eventually**: patchset that needs to be verified in alpha before backport
+- [ ] **No Backport (preferred)**: patchset for the next major stable
+
+#### (Optional) Justification
+- [ ] **Emergency security update**: patchset fixes CVEs, 0-days, etc
+- [ ] **Censorship event**: patchset enables censorship circumvention
+- [ ] **Critical bug-fix**: patchset fixes a bug in core-functionality
+- [ ] **Consistency**: patchset which would make development easier if it were in both the alpha and release branches; developer tools, build system changes, etc
+- [ ] **Sponsor required**: patchset required for sponsor
+- [ ] **Other**: please explain
+
+### Merging
+- [ ] Merge to `tor-browser` - `!fixups` to `tor-browser`-specific commits, new features, security backports
+- [ ] Merge to `base-browser` - `!fixups` to `base-browser`-specific commits, new features to be shared with `mullvad-browser`, and security backports
+  - **NOTE**: if your changeset includes patches to both `base-browser` and `tor-browser` please clearly label in the change description which commits should be cherry-picked to `base-browser` after merging
+
+### Issue Tracking
+- [ ] Link resolved issues with appropriate [Release Prep issue](https://gitlab.torproject.org/groups/tpo/applications/-/issues/?sort=updated_desc&state=opened&label_name%5B%5D=Release%20Prep&first_page_size=20) for changelog generation
+
+### Review
+
+#### Request Reviewer
+
+- [ ] Request review from an applications developer depending on modified system:
+  - **NOTE**: if the MR modifies multiple areas, please `/cc` all the relevant reviewers (since gitlab only allows 1 reviewer)
+  - **accessibility** : henry
+  - **android** : clairehurst, dan
+  - **build system** : boklm
+  - **extensions** : ma1
+  - **firefox internals (XUL/JS/XPCOM)** : ma1
+  - **fonts** : pierov
+  - **frontend (implementation)** : henry
+  - **frontend (review)** : donuts, richard
+  - **localization** : henry, pierov
+  - **macos** : clairehurst, dan
+  - **nightly builds** : boklm
+  - **rebases/release-prep** : dan, ma1, pierov, richard
+  - **security** : ma1
+  - **signing** : boklm, richard
+  - **updater** : pierov
+  - **misc/other** : pierov, richard
+
+#### Change Description
+
+<!-- Whatever context the reviewer needs to effectively review the patchset; if the patch includes UX updates be sure to include screenshots/video of how any new behaviour -->
+
+#### How Tested
+
+<!-- Description of steps taken to verify the change -->
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